Digital Guided Micro Prosthodontics 9789811902550, 9789811902567, 9811902550

Table of contents :
Preface
Acknowledgments
Contents
Authors and Contributors
About the Author
Contributors
1: Overview
1.1 Development and Requirements of Micro Dentistry
1.1.1 Different Levels of Visual Basis Bring Different Levels of Recognition
1.1.2 Development of Micro Dentistry
1.2 Application of Dental Microscope in Dental Specialties
1.2.1 Accuracy of Measurement Required by Each Dental Specialty Is Not the Same, and that of Endodontics and Prosthodontics Is Relatively Small
1.2.2 The Application of Microscope in Endodontics
1.2.3 The Application of Microscope in Periodontics and Dental Implantology
1.2.4 The Application of Microscope in Prosthodontics
1.2.5 The Application of Microscope in Dental Technology
1.2.6 The Application of Microscope in Teaching, Scientific Research, and Clinical Skill Training
1.3 Development and Advantages of Micro Prosthodontics
1.3.1 In the Naked-Eye Age, the Complications of Restoration Are Mostly Related to Unclear Vision
1.3.2 Reasons Why We Need Micro Prosthodontics
1.3.3 The Relationship Between Digital Micro Prosthodontics and Minimally Invasive Dentistry
Suggested Readings
Part I: Analysis, Design and Preclinical Preparation of Micro Prosthodontics
2: Theory and Practice of Target Restorative Space (TRS)
2.1 Definition and Classification of Target Restorative Space (TRS)
2.1.1 Definition
2.1.2 Classification
2.1.2.1 Classification of Target Restorative Space for Implant
2.1.2.2 Classification of Fixed Restorative Space
2.2 The Significance of Target Restorative Space (TRS) in Prosthodontics
2.2.1 The Significance of TRS in Aesthetic Restoration
2.2.1.1 Analysis and Design Phase Before Operation
2.2.1.2 Implementation Phase During Operation
2.2.2 The Significance of TRS in Implant Surgery
2.3 Classification and Manufacturing of TRS Guide
2.3.1 Classification of TRS Guides
2.3.1.1 Classified by Production Method
2.3.1.2 Classified by Purpose
2.3.2 Transparent Dental Membrane TRS Guide
2.3.3 3D Printing TRS Guide
2.3.4 Two-in-One TRS Guide for Tooth Preparation and Implantation
2.4 Application of Target Restorative Space (TRS) Guide in Preoperative Analysis and Design
2.4.1 Application of TRS Guide in Aesthetic Restoration of Anterior Teeth
2.4.1.1 Restoration Types of Internal and Mixed Space
2.4.1.2 Restoration Type of External Space
2.4.2 Application of TRS Guide in Functional Reconstruction of Oral and Maxillofacial System
2.4.3 Application of TRS Guide in Secondary Restoration
2.4.4 Application of TRS Guide in Dental Implant
2.5 Summary and Prospect
Suggested Readings
3: Microscope and Auxiliary Devices for Micro Prosthodontics
3.1 The Basic Structure and Working Principle of Dental Microscope
3.1.1 Definition of Dental Microscopes
3.1.2 Classification of Dental Microscopes
3.1.3 Basic Structures of Dental Operating Microscope
3.1.3.1 Optical Magnification System
3.1.3.2 Illumination System
3.1.3.3 Digital Imaging System
3.1.3.4 Supporting System of Dental Operating Microscope
3.2 Auxiliary Devices for Micro Prosthodontics
3.2.1 Ring Flash/Twin Flash Device Around the Objective Lens
3.2.2 Lingual/Palatal Reflector and Its Holder
3.2.3 Variable Diaphragm
3.2.4 Enamel Chisel
3.3 The Basic Set-Up and Instructions of Dental Operating Microscope
3.3.1 Set-Up and Precautions of Dental Operating Microscope
3.3.1.1 Set-Up Before Use
3.3.1.2 Reminder While in Use
3.3.1.3 Reminder After Use
3.3.2 Basic Adjustment of Dental Operating Microscope
3.3.2.1 Adjustment of Interpupillary Distance
3.3.2.2 Adjustment of Diopter
3.3.2.3 Adjustment of Light Intensity
3.3.2.4 Parfocalization
3.4 Summary and Prospect
Suggested Readings
4: Posture and Microscopic View of Prosthodontic Microsurgery
4.1 Dental Microsurgery Technique and Ergonomics
4.1.1 Definition of Ergonomics
4.1.2 The Connection Between Dental Microsurgery Technique and Ergonomics
4.1.3 Ergonomic Recommendations
4.2 Postures of Dental Microsurgery
4.2.1 Ergonomic Posture of Dental Microsurgery
4.2.1.1 The Position of Operator Chair
4.2.1.2 The Position of Patient’s Chair
4.2.1.3 The Placement of Microscope
4.2.1.4 Incorrect Posture of Dental Microsurgery
4.3 Microscopic View of Each Tooth
4.3.1 Microscopic View of Maxillary Anterior Teeth
4.3.1.1 The Labial Side of Maxillary Anterior Teeth
4.3.1.2 The Proximal Side of Maxillary Anterior Teeth
4.3.1.3 The Palatal Side of Maxillary Anterior Teeth
4.3.2 Microscopic View of Maxillary Posterior Teeth
4.3.2.1 The Buccal Side of Maxillary Posterior Teeth
4.3.2.2 The Palatal Side of Maxillary Posterior Teeth
4.3.2.3 The Occlusal Surface of Maxillary Posterior Teeth
4.3.3 Microscopic View of the Mandibular Anterior Teeth
4.3.3.1 The Labial Side of the Mandibular Anterior Teeth
4.3.3.2 The Lingual Side of the Mandibular Anterior Teeth
4.3.4 Microscopic View of the Mandibular Posterior Teeth
4.3.4.1 The Buccal Surface of the Mandibular Posterior Teeth
4.3.4.2 The Lingual Surface of the Mandibular Posterior Teeth
4.3.4.3 The Occlusal Surface of the Mandibular Posterior Teeth
4.4 Thoughts and Comments Regarding the Practice of Micro Prosthodontics
4.4.1 Using a Microscope Can Prolong the Career Longevity of Dentists and Improve Clinical Results
4.4.2 Microscopy Does Not Mean Minimal Invasiveness
4.4.3 Application of Dental Microscope in Prosthodontics Teaching
4.4.4 “Five Difficulties” in the Practice and Teaching of Microscopic Prosthodontics
4.4.5 Consensus Should Be Achieved on Microscopic Prosthodontic Teaching
4.5 Summary and Prospect
Suggested Readings
Part II: Sequential and Key Clinical Techniques for Digital Micro Prosthodontics
5: Pain Management and Comfortable Treatment in Micro Prosthodontics
5.1 Local Anesthetics and Local Anesthesia Methods
5.1.1 How to Choose Local Anesthetics
5.1.2 How to Choose Local Anesthesia Method
5.1.2.1 Nerve Block Anesthesia
5.1.2.2 Local Infiltration Anesthesia
5.1.2.3 Surface Anesthesia
5.1.3 How to Calculate Drug Dosage
5.1.4 Sedation
5.2 Clinical Operation Procedure
5.2.1 Evaluation and Preparation Before Anesthesia
5.2.1.1 Evaluation Before Anesthesia
5.2.1.2 Preparation of Anesthesia Instruments
5.2.2 Implementation of Anesthesia
5.2.2.1 Injection Pain Control
5.2.2.2 Local Anesthesia Procedure
5.2.3 Complications
5.2.3.1 Local Complications
5.2.3.2 Systemic Complications
5.2.3.3 Reasons for Poor Oral Local Anesthesia
5.3 Pain Control of Tooth Preparation
5.3.1 Principles and Mechanisms
5.3.2 Pain Control During and After Tooth Preparation
5.4 Pain Control of Dental Implantation
5.4.1 Principles and Mechanisms
5.4.2 Reasons for Pain after Dental Implantation
5.4.2.1 Anxiety
5.4.2.2 Pain Sensitivity
5.4.2.3 Pain Expectation
5.4.2.4 Flap
5.4.2.5 Implant Position
5.4.3 Pain Control After Dental Implantation
5.5 Summary and Prospect
Suggested Readings
6: Isolation of the Operative Field in Micro Prosthodontics: Practical Rubber Dam Technology
6.1 Rubber Dam and Accessories
6.1.1 Composition of Rubber Dam Kit
6.2 Basic Technology of Rubber Dam
6.2.1 Placement of Rubber Dam
6.2.1.1 Winged Technique
6.2.1.2 Rubber First Technique
6.2.1.3 Clamp First Technique
6.2.1.4 Bow Technique
6.2.1.5 Split Dam Technique
6.2.2 Reminder for Rubber Dam Placement
6.2.2.1 Protecting the Gums
6.2.2.2 Use of Dental Floss
6.2.2.3 Slide of the Rubber Dam
6.2.2.4 Removal of the Rubber Dam
6.3 Use of Rubber Dam in Special Situations
6.3.1 Gingival Sulcus Fluid or Saliva Microleakage
6.3.2 Large Defect of the Tooth or Poor Retention of the Crown
6.3.3 Isolation of PFM and Ceramic Crown
6.3.4 Isolation of Fixed Bridge Restoration
6.3.5 Tooth Neck Defect
6.3.6 Patients in Poor General Condition and Elderly Patients
6.4 Summary and Prospect
Suggested Readings
7: Introduction to Digital Micro Tooth Preparation Technology
7.1 Control of Tooth Preparation Amount
7.1.1 Biological Factor
7.1.2 Biochemical Factor
7.1.3 Esthetic and Functional Factor of Prosthesis
7.2 Control of the Preparation Shape
7.2.1 Requirements for the Shape of the Axial Surface of the Preparation
7.2.1.1 Basic Requirements
7.2.1.2 The Amount of Axial Preparation Is Not Uniform
7.2.2 The Control of the Position and Shape of the Preparation’s Margin
7.2.2.1 The Position of the Finish Line: The More Apical, the More Dangerous
7.2.2.2 The Shape and Size of the Preparation’s Margin Are Determined by the Shape and Size of the Tip of the Margin Preparation Bur
7.3 Instrument Selection for Tooth Preparation
7.3.1 Types and Selection of Cutting Bur for Tooth Preparation
7.3.1.1 The Structure of Bur and ISO Standard
7.3.1.2 Selection of Silicon Carbide Bur
7.3.1.3 Selection of Tungsten Carbide Bur
7.3.1.4 Introduction to HX-6 Depth Cutting Scaled Bur Kit
7.3.2 Types and Selection of Dental Handpiece and Motors
7.3.2.1 Classification of Dental Handpieces According to Operation Speed
7.3.2.2 Classification of Handpiece Motor According to Driving Mode
7.4 Application of TRS Guide in Tooth Preparation
7.4.1 Classification According to the Purpose of Use
7.4.1.1 Tooth Preparation Guide
7.4.1.2 TRS Guide for Tooth Preparation Combined with Implant Surgery
7.4.2 Classification According to Manufacturing Technology
7.4.2.1 Silicone TRS Guide
7.4.2.2 Transparent Membrane TRS Guide
7.4.2.3 3D Printing TRS Guide
7.5 Classification and Characteristics of the Existing Micro Tooth Preparation Techniques
7.5.1 Micro Groove Reference Tooth Preparation Technique
7.5.1.1 Horizontal Groove Reference Tooth Preparation Technique
7.5.1.2 Vertical Groove Reference Tooth Preparation Technique
7.5.2 Micro Hole Reference Tooth Preparation Technique
7.5.2.1 Accuracy
7.5.2.2 High Efficiency
7.5.2.3 Minimal Invasiveness
7.6 Clinical Workflow and Preparation Method of High-Precision Margin
7.6.1 Three Determinations
7.6.1.1 Determine the Material of the Target Fixed Prosthesis
7.6.1.2 Determine the Position of the Margin of the Preparation
7.6.1.3 Determine the Shape and Size Design of the Margin of the Preparation
7.6.2 Three Choices
7.6.3 Three Steps
7.6.3.1 Preliminary Preparation of the Margin
7.6.3.2 Elaborate Preparation of the Margin
7.6.3.3 Final Polishing of the Margin
7.7 Summary and Prospect
Suggested Readings
8: Digital Impression Technology
8.1 Classification and Characteristics of Digital Impression
8.1.1 Classification of Digital Impression
8.1.1.1 Digital Intraoral Scanning System
8.1.1.2 Digital Extra-oral Scanning System
8.1.2 Characteristics of Digital Impression
8.2 Operation Procedure of Digital Intraoral Scanning System
8.2.1 Installation of Digital Intraoral Scanning System
8.2.2 Introduction to Home Page of Intraoral Scanning Software
8.2.3 Case Management in Intraoral Scanning Software
8.2.4 Scanning Scheme and Scan and Image in Intraoral Scanning Software
8.2.4.1 Scanning Scheme
8.2.4.2 Scan and Image
8.2.5 Processing of Digital Intraoral Scanning Model
8.2.5.1 Edit
8.2.5.2 Base
8.2.5.3 Cervical Margin
8.2.5.4 Inspection of Undercut
8.2.5.5 Inspection of Occlusion Distance
8.2.5.6 Comparison
8.2.6 Storage and Export of Digital Intraoral Scanning Data
8.3 Common Problems and Solutions of Digital Impression
8.3.1 Common Problems and Solutions About Hardware
8.3.1.1 Common Problems
8.3.1.2 Solution
8.3.2 Common Problems and Solutions About Software
8.3.2.1 Scanning Interruption
8.3.2.2 Scanning Is Not Smooth
8.3.2.3 Discontinuity of Scanning Data
8.4 Summary and Prospect
Suggested Readings
9: Digital Depth-Hole-Guiding Micro Tooth Preparation for Porcelain Veneer
9.1 Overview and Indications of Porcelain Veneer
9.1.1 The Indications of Porcelain Veneer
9.1.2 The Characteristics of Porcelain Veneer
9.1.3 Materials of Porcelain Veneer
9.1.4 Types of Porcelain Veneer
9.2 Design of Targeted Restorative Space (TRS) and Porcelain Veneer Preparation
9.2.1 TRS Design of Porcelain Veneer
9.2.2 Preparation Design of Porcelain Veneer
9.2.2.1 Porcelain Thickness
9.2.2.2 Incisal Preparation
9.2.2.3 Proximal Preparation
9.2.2.4 Position of the Gingival Margin
9.2.2.5 Finish Line Shape
9.3 The Clinical Protocol of Micro Tooth Preparation with Digital Guide for Porcelain Veneer
9.3.1 Veneer Preparation Using the Silicone Rubber Guide
9.3.1.1 Data Collection and Analysis and Design of Aesthetic Line-Plane Relationship
9.3.1.2 Tooth Preparation Using Silicone Rubber Guide
9.3.2 Veneer Preparation Using the Transparent Vacuum-Formed TRS Guide
9.3.2.1 Data Collection and Analysis and Design of Aesthetic Line-Plane Relationship
9.3.2.2 Tooth Preparation Using the Transparent Vacuum-Formed TRS Guide
9.3.3 Veneer Preparation Using 3D Printing TRS Guide
9.3.3.1 3D Printing TRS Guide with Uniform Thickness
9.3.3.2 Tooth Preparation Using 3D Printing TRS Guide of Uniform Thickness
9.3.4 Finishing and Polishing
9.3.4.1 Finishing the Prepared Tooth
9.3.4.2 Polishing the Prepared Tooth
9.4 Gingival Retraction Technique Under a Microscope
9.4.1 Microscope Field of View for Gingival Retraction
9.4.1.1 Single-Cord Technique
9.4.1.2 Double-Cord Technique
9.4.2 The Procedure of Gingival Retraction Under a Microscope
9.5 Impression Making and Provisional Restoration
9.5.1 Impression Making
9.5.1.1 One-Step Technique
9.5.1.2 Two-Step Technique
9.5.2 Provisional Restoration
9.6 Overview and Indications of Partial Porcelain Veneers
9.6.1 Indications and Contraindications of Partial Porcelain Veneer
9.6.2 Materials for Partial Porcelain Veneer
9.6.3 TRS Design for Partial Porcelain Veneer
9.6.4 Preparation Requirements for Partial Porcelain Veneer
9.6.4.1 Remove the Decayed Material
9.6.4.2 Prepare a Shape with Sufficient Enamel Bonding Surface
9.6.5 Preparations for Tooth Preparation of Partial Porcelain Veneer
9.6.5.1 Identify the Patient’s Requirements and Exam on the Tooth Defect
9.6.5.2 Shade Selection
9.6.6 Preparation of Various Types of Dental Veneers
9.6.6.1 Preparation of Incisal Porcelain Veneer
9.6.6.2 Preparation of Labial Porcelain Veneer
9.6.6.3 Preparation of Proximal Porcelain Veneer
9.7 Summary and Prospect
Suggested Readings
10: Digital Micro Tooth Preparation for Posterior Indirect Adhesive Restorations
10.1 Overview of Posterior Indirect Adhesive Restorations
10.1.1 The Advantages and Disadvantages of PIAR
10.1.1.1 The Advantages of PIAR
10.1.1.2 The Disadvantages of PIAR
10.1.2 Material Selection for PIAR
10.1.2.1 Metal Material
10.1.2.2 Ceramic Material
10.1.2.3 Composite Resin Materials
10.1.3 Types of PIAR
10.2 Preparation Design of Posterior Indirect Adhesive Restoration
10.2.1 The Amount of Preparation
10.2.2 The Principle of Posterior Indirect Adhesive Restoration Preparation
10.2.2.1 Remove All Caries
10.2.2.2 Remove Weak Tooth Tissue
10.2.2.3 Prepare a Cavity with Retention and Resistance
10.2.2.4 Provide Enough Bonding Surface
10.2.2.5 The Position of the Cavity Edge Should Be Easy for Bonding
10.3 Micro Preparation Protocol for Posterior Indirect Adhesive Restorations
10.3.1 Basic Principles of PIAR Preparation
10.3.2 Preparation Before Tooth Preparation
10.3.3 Preparation Process of Micro Preparation Guided by TRS Guide
10.3.4 Preparation for Single-Surface PIAR
10.3.4.1 Class I Cavity
10.3.4.2 Buccal Wedge-Shaped Defect
10.3.5 Preparation for MO/DO PIAR
10.3.5.1 Occlusal Preparation
10.3.5.2 Proximal Preparation
10.3.5.3 The Finishing of the Margin
10.3.5.4 Polishing
10.3.5.5 Immediate Dentin Sealing and Temporary Restoration
10.4 Summary and Prospect
Suggested Readings
11: Digital Depth-Hole-Guiding Micro Preparation for All-Ceramic Crown
11.1 Overview and Indications of All-Ceramic Crown
11.1.1 Indications of All-Ceramic Crown
11.1.2 Contraindications of All-Ceramic Crown
11.2 Classification of All-Ceramic Material
11.2.1 Slip-Casting Ceramic
11.2.2 Castable Glass Ceramic
11.2.3 Pressed Castable Ceramic
11.2.4 Infiltrated Ceramic
11.2.5 Machinable Ceramic
11.2.6 Zirconia Ceramic or Zirconia-Toughened Ceramic
11.2.7 Nanocomposite Ceramic
11.2.8 Ceramic-Resin Composite
11.3 The Clinical Protocol of Digital Depth-Hole-Guiding Micro Tooth Preparation for All-Ceramic Crown
11.3.1 Analysis and Design Phase
11.3.2 Micro Tooth Preparation of  Anterior Teeth Under the Guidance of the Transparent Vacuum-Formed TRS Guide
11.3.2.1 Placement of TRS Guide
11.3.2.2 Buccal and Palatal Preparation
11.3.2.3 Incisal Preparation
11.3.2.4 Proximal Preparation
11.3.2.5 Finishing of Preparation Margin and Surface
11.3.3 Micro Tooth Preparation of Anterior Teeth Under the Guidance of the 3D Printing TRS Guide of Non-uniform Thicknesses
11.3.3.1 Manufacturing and Try-In of Non-uniform-Thick 3D Printing TRS Guide
11.3.4 Impression and Temporary Restoration
11.3.4.1 Impression
11.3.4.2 Fabrication of Temporary Crown
11.4 Summary and Prospect
Suggested Readings
12: Immediate Dentin Sealing and Micro Bonding
12.1 Overview and Mechanism of Adhesion
12.1.1 Concept of Adhesive
12.1.2 Mechanism of Adhesion
12.1.2.1 Mechanical Interlocking
12.1.2.2 Chemical Bond Force
12.1.2.3 Intermolecular Force
12.1.3 Type of Adhesives
12.1.3.1 Classification by Curing Method
12.1.3.2 Classification by the Adherend
12.1.4 Bonding of Enamel
12.1.4.1 The Structure of Enamel
12.1.4.2 The Importance of Enamel Bonding
12.1.4.3 Surface Conditioning of Enamel
12.1.5 Bonding of Dentin
12.1.5.1 The Structure of Dentin
12.1.5.2 Surface Conditioning of Dentin
12.1.5.3 Procedures for Different Bonding Systems
12.1.6 Immediate Dentin Sealing (IDS)
12.1.6.1 The Concept of IDS
12.1.6.2 Mechanism of IDS
12.1.6.3 Choice of Dentin Bonding Adhesive (DBA) in Immediate Dentin Sealing (IDS)
12.1.6.4 Procedures of IDS
12.1.7 The Treatments of the Ceramic Prosthesis
12.1.7.1 Surface Cleaning
12.1.7.2 Surface Roughening
12.1.7.3 Chemical Coupling
12.1.7.4 Silicon Coating
12.1.7.5 Summary
12.1.8 Cementing of Temporary Restorations
12.2 Micro Bonding Process of Zirconia- and Glass-Based Ceramics
12.2.1 Characteristics of Bonding of Different Restorative Materials
12.2.1.1 Glass-Based Ceramic
12.2.1.2 Zirconia Ceramic
12.2.2 Surface Conditioning of Different Restorative Materials
12.2.2.1 Glass-Based Ceramic
12.2.2.2 Zirconia Ceramic
12.2.3 Surface Conditioning of the Preparation (Abutment Tooth) Which Is to Be Repaired with Different Restorative Materials
12.2.3.1 Surface Conditioning of the Preparation for Glass-Based Ceramic Restoration
12.2.3.2 Surface Conditioning of the Preparation for Zirconia Ceramic Restoration
12.3 Micro Bonding Process of Porcelain Veneer
12.3.1 Selection of Adhesive Resin
12.3.2 Try-In and Preparation
12.3.3 Surface Conditioning of the Tooth
12.3.4 Surface Conditioning of the Porcelain Veneer
12.3.5 Placement
12.3.6 Occlusal Check and Adjustment
12.4 Micro Bonding Process of All-Ceramic Crown
12.4.1 Selection of Adhesive
12.4.2 Try-In and Preparation
12.4.3 Occlusal Check and Adjustment
12.4.4 Surface Conditioning of the Tooth Surface
12.4.5 Surface Conditioning of the All-Ceramic Crown
12.4.6 Placement
12.5 Summary and Prospect
Suggested Readings
Part III: Complications and Treatment After Micro-prosthodontics
13: Complications and Treatment After Micro Prosthodontics
13.1 Routine Maintenance
13.1.1 Brush Teeth and Use Dental Floss Correctly
13.1.2 Receive Regular Scaling and Treatment in Time If There Is Any Problem
13.1.3 Apply Fluoride and Prevent Secondary Caries
13.2 Complications and Treatment
13.2.1 Chipping Fracture of Porcelain
13.2.2 Porcelain Cracking
13.2.3 Debonding of Prosthesis
13.2.3.1 Adhesive Remains on the Tooth
13.2.3.2 Adhesive Remains on the Restoration
13.2.4 Dental Allergy
13.2.5 Abutment Fracture
13.2.6 Discoloration at the Margin of the Prosthesis
13.2.7 Dental Pulp Devitalization and Secondary Caries
13.3 Summary and Prospect
Suggested Readings
Part IV: Clinical Rehabilitation of Secondary Aesthetic Porcelain Restoration
14: Decisions on Clinical Rehabilitation of Secondary Aesthetic Porcelain Restoration
14.1 Possible Complications of Secondary Aesthetic Porcelain Restoration
14.1.1 Hypersensitivity of Abutment Teeth
14.1.2 Spontaneous Pain of Abutment Teeth
14.1.3 Loosening, Cracking and Discolouration of Abutment Teeth
14.1.4 Occurrence of Exacerbation of Periodontal Disease
14.1.5 Discolouration of Restoration
14.1.6 Loosening and Falling Off of Restoration
14.1.7 Cracking, Breaking and Perforation of Restoration
14.1.8 Dysfunction and Psychological Problems
14.2 Clinical Decision Tree of Secondary Aesthetic Porcelain Restoration Guided by TRS Guide
14.2.1 Psychological Evaluation
14.2.2 Previous Treatment Evaluation
14.2.3 Prosthodontic Decision After Removing the Old Restoration (Fig. 14.6)
14.3 Typical Cases of Secondary Porcelain Aesthetic Repair and Retreatment
14.3.1 Secondary Aesthetic Porcelain Restorations in the Anterior Area
14.3.1.1 A Case of Secondary Aesthetic Porcelain Restoration Aided by TRS Guide for a Maxillary Anterior Tooth
14.3.1.2 An Example of Secondary Aesthetic Porcelain Restoration for the Upper Central Incisors Aided by the TRS Guide
14.3.1.3 A Case of Secondary Aesthetic Porcelain Restoration for Upper Right Central Incisor Aided by TRS Guide
14.3.1.4 A Case of Secondary Aesthetic Porcelain Restoration of Maxillae and Mandible Aided by TRS Guide
14.3.1.5 A Case of Joint Repair for Tooth Defects and Dentition Defects Using Printing Non-Uniformly-Thick Titanium Guide
14.3.1.6 A Case of Implant Surgery Using the HX Measuring-and-Guiding Kit for Implant for Posterior Secondary Restoration
14.4 Summary and Prospect
Suggested Readings
15: Occlusal Reconstruction Under the Guidance of Target Restorative Space
15.1 Comprehensive Assessment Before Occlusal Reconstruction
15.1.1 Clinical Consultation and Risk Assessment
15.1.2 Examination of the Oral and Maxillofacial System
15.1.3 Radiographic Examination
15.1.4 Mounting of Diagnosis Casts onto the Articulator
15.2 Typical Cases of Occlusion Reconstruction Aided by the TRS Guide
15.2.1 A Case of Secondary Aesthetic and Functional Porcelain Restoration of Maxillae and Mandible Aided by TRS Guide
15.2.2 A Case of Secondary Aesthetic Porcelain Restoration of Maxillae and Mandible Aided by TRS Guide
15.2.3 A Case of Occlusal Reconstruction Restored by Implant-Supported Fixed Prosthesis with the Aid of Whole-Process Digital Guidance
15.3 Clinical Application of Occlusion Adjusting Guide in Occlusal Reconstruction
15.3.1 Digital Clinical Workflow of Occlusion Reconstruction for Cases with Insufficient Occlusal Space (Fig. 15.120)
15.3.2 A Clinical Case of Designing Occlusion Adjusting Guide
15.4 Summary and Prospect
Suggested Readings
16: Cases of Digital Micro Prosthodontics Guided by Target Restorative Space
16.1 Typical Cases of Digital Micro Restoration Guided by Wax-Up Surface
16.1.1 A Case of Crown Lengthening Combining with Porcelain Veneer Restoration of Maxillary Anterior Tooth Guided by Mock-Up Surface
16.2 Typical Cases of Digital Micro Restoration Guided by Silicone Index
16.2.1 A Case of All-Ceramic Crown of Maxillary Anterior Tooth with ETRS Guided by Silicone Index
16.3 Typical Cases of Digital Micro Restoration Aided by Transparent Dental Membrane TRS Guide
16.3.1 A Case of Digital Micro Restoration of Traumatic Maxillary Anterior Tooth with Ceramic Veneer Aided by Transparent Dental Membrane TRS Guide
16.3.2 A Case of Porcelain Inlay Restoration of Elongated and Rotated Maxillary Anterior Teeth Aided by Transparent Dental Membrane TRS Guide
16.3.3 A Case of Porcelain Inlay Restoration of Defected Upper Anterior Teeth Aided by Transparent Dental Membrane TRS Guide
16.3.4 A Case of Porcelain Veneer Restoration of Maxillary and Mandibular Tetracycline Teeth Aided by Transparent Dental Membrane TRS Guide
16.4 Typical Cases of Digital Micro Restoration Aided by 3D Printing TRS Guide with Uniform Thickness
16.4.1 A Case of Digital All-Ceramic Restorations of Maxillary and Mandibular Anterior Tooth with Exogenous Severe Erosion and Extensive Caries Aided by 3D Printing TRS Guide with Uniform Thickness
16.5 Typical Cases of Digital Micro Restoration Aided by 3D Printing TRS Guide with Non-uniform Thickness
16.5.1 A Case of Digital All-Ceramic Crown of Maxillary Rotated Anterior Tooth Aided by 3D Printing TRS Guide with Non-uniform Thickness
16.5.2 A Case of Digital All-Ceramic Veneer of Maxillary Anterior Dental Fluorosis Aided by 3D Printing TRS Guide with Non-uniform Thickness
16.5.3 A Case of Immediate Restoration of Prefabricated Crown Aided by 3D Printing TRS Guide with Non-uniform Thickness
16.6 Typical Cases of Digital Micro Restoration Aided by Two-in-One TRS Guide for Implant Surgery and Tooth Preparation
16.6.1 A Case of Digital Micro Restoration Aided by Two-in-One TRS Guide for Implant Surgery and Tooth Preparation
16.7 Summary and Prospect
Suggested Readings

Citation preview

Haiyang Yu

Digital Guided Micro Prosthodontics

123

Digital Guided Micro Prosthodontics

Haiyang Yu

Digital Guided Micro Prosthodontics

Haiyang Yu Department of Prosthodontics, State Key Laboratory of Oral Diseases National Clinical Research Center for Oral Diseases West China Hospital of Stomatology, Sichuan University Chengdu, China

ISBN 978-981-19-0255-0    ISBN 978-981-19-0256-7 (eBook) https://doi.org/10.1007/978-981-19-0256-7 © Springer Nature Singapore Pte Ltd. and People's Medical Publishing House 2022 This work is subject to copyright. All rights are reserved by the Publishers, whether the whole or part of the material is concerned, specifically the rights of reprinting, reuse of illustrations, recitation, broadcasting, reproduction on microfilms or in any other physical way, and transmission or information storage and retrieval, electronic adaptation, computer software, or by similar or dissimilar methodology now known or hereafter developed. The use of general descriptive names, registered names, trademarks, service marks, etc. in this publication does not imply, even in the absence of a specific statement, that such names are exempt from the relevant protective laws and regulations and therefore free for general use. The publishers, the authors, and the editors are safe to assume that the advice and information in this book are believed to be true and accurate at the date of publication. Neither the publishers nor the authors or the editors give a warranty, express or implied, with respect to the material contained herein or for any errors or omissions that may have been made. The publishers remain neutral with regard to jurisdictional claims in published maps and institutional affiliations. This Springer imprint is published by the registered company Springer Nature Singapore Pte Ltd. The registered company address is: 152 Beach Road, #21-01/04 Gateway East, Singapore 189721, Singapore

Preface

In 1609, Galileo looked at the vast starry sky for the first time using his self-made rough telescope. His immortal work gave birth to the use and popularization of astronomical telescopes and radio telescopes and gave birth to modern astronomy focusing on the vast and infinite universe. Similarly, in 1665, the British scientist Robert Hook observed the tiny plant cork tissue with a microscope and found that it consisted of many microscopic honeycomb cavities and named them as cell. With the widespread application of microscopes that can discover and observe small “cells” in medicine, the birth of biomedicine at the microscopic scale has promoted a big step forward in medical cognition, enabling doctors to benefit more patients. Looking back at the development of stomatology, we find that the application of microscopes for more than 30 years has promoted the improvement of micro-root canal treatment in dental endodontics, allowing dentists to see root canal system more clearly and also to obtain unprecedented clinical efficacy. Due to the significant success of root canal treatment, the dental microscope has a slightly narrow name “root canal microscope.” In fact, microscope is also suitable for many other aspects of oral clinical diagnosis and treatment more than endodontics. Compared with other dental specialties, although the use of microscope in prosthodontics comes a bit late, it also opens a window of promising future for doctors: finer operations, clearer fields of vision, and more predictable curative effects. This fully fits the concept of minimally invasive restoration based on tooth structure preservation, vital pulp protection, periodontal health, and harmonious function. But unlike mature micro-root canal treatments, the use of microscope in prosthodontics is more challenging: clinicians need the microscope with a larger field of view, a larger depth of field, and more accurate color reproduction, while how to prevent water mist and how to quickly switch between multiple teeth are problems to be solved. Therefore, many clinicians have thought that micro-repair is too troublesome in recent years or simply said that micro-repair is a gimmick! Historically speaking, these views are not unreasonable, showing that micro-repair is difficult. In general, the development of micro prosthodontics is not fast or smooth. In terms of problems faced in the development of micro-repair, what hinders its promotion and development? I think the first obstacle is the insufficient cognitive changes about experience-oriented clinical-end. There is a difference between diagnosis and treatment in the microscopic field and that with the naked eye. It’s difficult to exert the advantages of operating in the microscopic field when implementing experience-oriented clinical techniques that belong to the age of naked eye under the microscope, and it is not true micro-repair. On the other hand, the successful experience accumulated in operations under the naked eye cannot support prosthodontics under the microscope. We must correctly understand and solve the “five major difficulties and challenges” in the practice of micro prosthodontics: 1. Difficulty in changing from direct-view operation to under-microscope operation (or on-­ screen operation) 2. Difficulty in switching of patient’s position and operator’s posture between the naked-eye view and microscopic fields v

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3. Difficulty in changing from a single pivot to multiple pivots 4. Difficulty in cooperation of 4-handed operation under the influence of water mist . 5. Difficulty in upgrading of guidance methods for tooth preparation from free hands to digital techniques which are not base on “experience” (physical or virtual guide , accuracy of 0.1–0.3 mm). The second obstacle is about numerical problems, that is, the quantitative requirements and relationship of restoration space transfer. There are many numerical requirements in prosthodontics, generally accurate to hundred microns. In the current prosthetic sequence treatment, the clinical workflow, from impression, cast making, tooth preparation, and temporary restoration to final restoration, can hardly achieve the accurate correspondence of restorative space between steps during the transferring process, because these operations are based on empiricism and lack of foundation of reliable numerical values. The core difficulty lies in whether those numerical requirements in prosthodontics are necessary and authentic and how to achieve one-to-one volumetric space transfer which relies on quantitative relationship instead of uncertain “experience” in the sequence clinical workflow. Regardless of comments on micro prosthodontics, most experts are approving the final restorative effect. Especially in the past 10 years, with the rapid development and popularization of aesthetic restoration, adhesive restoration, and microscope technology, it has become possible to perfect and mature micro prosthodontics. Thanks to the surgical microscope having lager magnifications, deeper depth of field and lower price after 30-year development of root canal microscope, prosthodontist can get rid of interference of water mist and have a clear operative view. Even using the traditional restoration technology under the microscope, dentists can see more clearly, so that the complication can be reduced. More importantly, the magnification and microscopy of visual scale allows the restoration technology to be upgraded from the naked-eye view to a magnified and microscopic field of vision. Meanwhile, some new techniques like “depth-hole-guiding tooth preparation” which can achieve the accuracy up to 0.1 mm have been launched. More and more specialists have accepted micro restoration technology especially micro operation in aesthetic areas which is not all time-consuming and troublesome. Fixed prosthetics has entered the microscopic age hesitantly, and unstoppable changes are happening to prosthodontics now. When talking about micro prosthodontics, we always mention aesthetic prosthodontics. Why is esthetic prosthodontics the starting point for the development of micro prosthodontics? Compared to the posterior teeth, the operation of anterior teeth is more convenient. Furthermore, the anterior teeth play an essential role of esthetics in people’s appearance, so everyone pays more attention about his teeth which will be exposed during the social smile. In clinical practice, it is common to find problems in patients’ posterior teeth, such as periodontal and endodontic disease. However, because these diseases do not affect the appearance, patients often are not eager to receive treatment promptly. Once an esthetic problem occurs to anterior teeth influencing the appearance, they come to the clinic, hoping to immediately and even merely solve the problem of anterior teeth. So problems ensue: (1) How to ensure the periodontal and endodontic health? How to keep the stability of pink and white aesthetics in the long term? (2) The poorly controlled or uncontrolled plaque will endanger the abutment teeth and unrepaired teeth, which increases the risk of caries in patients. (3) Decompensation of occlusion and other functions might affect the final aesthetic restoration effect of anterior teeth. Therefore, due to the clinical needs of aesthetics, clinicians need multidisciplinary knowledge and skills. Now microscopes providing clear vision make it possible for clinicians to discover problems earlier and have become an useful tool for them to succeed one step ahead.

Preface

Preface

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Aesthetic restoration is a difficult and hot topic in dental diagnosis and treatment, but it should not be overpopularized. As aesthetics is one of the many functions of the oral and maxillofacial system, aesthetic restoration and functional restoration cannot be simply and rudely placed on opposite sides. Aesthetics, chewing, pronunciation, and other functions are all part of the main functions of the oral and maxillofacial system. On the other hand, aesthetic restoration in the broad sense is mostly about simulation where the final restoration is fabricated according to the standardized contours and colors of natural teeth and the standards and specifications adopted are universal for various dental treatments instead of unique for aesthetic restoration. Aesthetic restoration in the narrow sense focuses more on individuation of restorations which even have shapes and colors different from standardized pattern, using the principle, technical processes, and clinical strategies of individually high aesthetics. Therefore, do not overpopularize aesthetics. The conventional aesthetic restoration is mostly simulation repair of copying normal anatomical features, while individualized diagnosis and treatment of highly aesthetic restoration must be a personal thing. In clinical practice, we also see another iatrogenic impulse, that is, the overtreatment of aesthetic repair often ignores the normal function of chewing and speech on which aesthetic repair depends and also ignores the periodontal health, tooth structure preservation and vital pulp protection. In order to obtain short-term aesthetic results, freehand techniques under the naked eye randomly cuts the tooth tissue based on experience and adopt too deep subgingival margins and other poor design and operation for short-term aesthetics, resulting in many patients and dentists paying an unbearable price. The philosophy of my practice is patient safety, that is, to achieve long-term and stable treatment effect for patients with minimal iatrogenic injury and minimal cost. In the past 30 years of clinical practice, our team has carefully analyzed restoration cases with naked eyes and under magnifying loupe and microscopes and gone through phases of passive attempt in operating under a microscope, gradually liking it and finally being addicted to it. Backing by the State Key Laboratory of Oral Diseases and the National Clinical Key Specialty of Prosthodontics, our team has collected some clinical data on micro prosthodontics. Many dentists in our team are the native generation of micro-repair who have been using microscope since the beginning of their practice and have excellent clinical skills. Through years of study and accumulation, we have proposed some prosthodontic techniques which are suitable for the microscopic scale, such as micro depth-hole-guiding tooth preparation technique, TRS guide technique, and physical measurement technique of restorative space and implantation site. There are more and more dentists learning to use these practical techniques, ending in operating more proficiently with shorter learning curve and realizing the significant effects of tooth preservation, vital pulp, and periodontal protection. The clinical operations of micro prosthodontics are not all very time-­consuming. Our micro-repair in the aesthetic area requires much shorter operating time which is almost near the time the naked-eye operation needs, well received by dentists and patients. Over the past few years, more than 30 hands-on workshops in micro tooth preparations have been held. At the first China Microscopy Conference in 2018. I was honored to host the first hands-on workshop and introduce new understandings and techniques for micro tooth preparation: such as depth-hole-guiding tooth preparation, cutting surface design, margin lifting technique, TRS guide technique, etc. These techniques of micro prosthodontics give fixed prosthetics more possibility and promising future! Although my team and I had researched on micro prosthodontics and collected some cases over these years, I was still entangled for a long time when Director Liu Hongxia invited me to

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write this book 4 years ago. Through repeatedly sorting out and analyzing available cases, I was thinking about and tried to answer these questions: How to turn experience-oriented tooth preparation into controllable and measurable tooth preparation with digital guidance which is simple and predictable? Why is the guide often used for dental implant instead of preparing teeth? I submitted a manuscript 2 years ago, but had it back a few days later to perfect the theory and logic and verify cases. In short, the best work seems to be on the road forever! Thanks to our team for support and encouragement! Suggestions and comments about this book are always welcome! Chengdu, China December, 2018

Haiyang Yu

Acknowledgments

I’d like to express my gratitude to Zumax (Suzhou), Color Cube (Tianjin), Gaofeng (Jiangsu), Bien Air (Switzerland), and other companies for their facilitating the transformation of our patents such as surgical microscope and accessories for restoration, virtual repair software, scaled burs, TRS guide, etc., into clinical practice. Turning the patents of invention into productivity has realized our TRS theory and a series of micro-repair techniques. I would also like to show my gratitude to Koukou (Chengdu) for their dedicated work of manufacturing restoration. I would also like to thank Chief Technician Li Yue, my assistant Yutian Huang, and each of the clinical and laboratory contributors for their contribution to this project and cases in this book. Last but not the least, I would like to recognize appreciation for the People’s Medical Publishing House team, especially Director Liu Hongxia and Editor Fang Yi, and Springer Team for their organization, editing, and relentless dedication.

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Contents

1 Overview ���������������������������������������������������������������������������������������������������������������������   1 1.1 Development and Requirements of Micro Dentistry�������������������������������������������   2 1.1.1 Different Levels of Visual Basis Bring Different Levels of Recognition�����������������������������������������������������������������������������������������   2 1.1.2 Development of Micro Dentistry�������������������������������������������������������������   3 1.2 Application of Dental Microscope in Dental Specialties�������������������������������������   3 1.2.1 Accuracy of Measurement Required by Each Dental Specialty Is Not the Same, and that of Endodontics and Prosthodontics Is Relatively Small���������������������������������������������������   3 1.2.2 The Application of Microscope in Endodontics �������������������������������������   4 1.2.3 The Application of Microscope in Periodontics and Dental Implantology�������������������������������������������������������������������������   4 1.2.4 The Application of Microscope in Prosthodontics����������������������������������   4 1.2.5 The Application of Microscope in Dental Technology���������������������������   4 1.2.6 The Application of Microscope in Teaching, Scientific Research, and Clinical Skill Training �������������������������������������   5 1.3 Development and Advantages of Micro Prosthodontics�������������������������������������   5 1.3.1 In the Naked-Eye Age, the Complications of Restoration Are Mostly Related to Unclear Vision�����������������������������������������������������   5 1.3.2 Reasons Why We Need Micro Prosthodontics ���������������������������������������   5 1.3.3 The Relationship Between Digital Micro Prosthodontics and Minimally Invasive Dentistry�����������������������������������������������������������   6 Suggested Readings �����������������������������������������������������������������������������������������������������   7 Part I Analysis, Design and Preclinical Preparation of Micro Prosthodontics 2 Theory  and Practice of Target Restorative Space (TRS) ���������������������������������������  11 2.1 Definition and Classification of Target Restorative Space (TRS)�����������������������  11 2.1.1 Definition�������������������������������������������������������������������������������������������������  11 2.1.2 Classification�������������������������������������������������������������������������������������������  11 2.2 The Significance of Target Restorative Space (TRS) in Prosthodontics�������������  15 2.2.1 The Significance of TRS in Aesthetic Restoration ���������������������������������  15 2.2.2 The Significance of TRS in Implant Surgery�������������������������������������������  18 2.3 Classification and Manufacturing of TRS Guide�������������������������������������������������  18 2.3.1 Classification of TRS Guides�������������������������������������������������������������������  19 2.3.2 Transparent Dental Membrane TRS Guide���������������������������������������������  20 2.3.3 3D Printing TRS Guide���������������������������������������������������������������������������  20 2.3.4 Two-in-One TRS Guide for Tooth Preparation and Implantation�����������  21 2.4 Application of Target Restorative Space (TRS) Guide in Preoperative Analysis and Design�������������������������������������������������������������������  21 2.4.1 Application of TRS Guide in Aesthetic Restoration of Anterior Teeth �������������������������������������������������������������������������������������  21 xi

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2.4.2 Application of TRS Guide in Functional Reconstruction of Oral and Maxillofacial System �����������������������������������������������������������  22 2.4.3 Application of TRS Guide in Secondary Restoration�����������������������������  24 2.4.4 Application of TRS Guide in Dental Implant �����������������������������������������  24 2.5 Summary and Prospect ���������������������������������������������������������������������������������������  24 Suggested Readings �����������������������������������������������������������������������������������������������������  26 3 Microscope  and Auxiliary Devices for Micro Prosthodontics���������������������������������  27 3.1 The Basic Structure and Working Principle of Dental Microscope���������������������  27 3.1.1 Definition of Dental Microscopes�����������������������������������������������������������  27 3.1.2 Classification of Dental Microscopes �����������������������������������������������������  28 3.1.3 Basic Structures of Dental Operating Microscope����������������������������������  29 3.2 Auxiliary Devices for Micro Prosthodontics�������������������������������������������������������  35 3.2.1 Ring Flash/Twin Flash Device Around the Objective Lens���������������������  37 3.2.2 Lingual/Palatal Reflector and Its Holder�������������������������������������������������  37 3.2.3 Variable Diaphragm���������������������������������������������������������������������������������  38 3.2.4 Enamel Chisel �����������������������������������������������������������������������������������������  38 3.3 The Basic Set-Up and Instructions of Dental Operating Microscope�����������������  39 3.3.1 Set-Up and Precautions of Dental Operating Microscope�����������������������  39 3.3.2 Basic Adjustment of Dental Operating Microscope �������������������������������  40 3.4 Summary and Prospect ���������������������������������������������������������������������������������������  42 Suggested Readings �����������������������������������������������������������������������������������������������������  42 4 Posture  and Microscopic View of Prosthodontic Microsurgery�����������������������������  43 4.1 Dental Microsurgery Technique and Ergonomics�����������������������������������������������  43 4.1.1 Definition of Ergonomics�������������������������������������������������������������������������  43 4.1.2 The Connection Between Dental Microsurgery Technique and Ergonomics���������������������������������������������������������������������  43 4.1.3 Ergonomic Recommendations�����������������������������������������������������������������  43 4.2 Postures of Dental Microsurgery�������������������������������������������������������������������������  44 4.2.1 Ergonomic Posture of Dental Microsurgery �������������������������������������������  44 4.3 Microscopic View of Each Tooth�������������������������������������������������������������������������  46 4.3.1 Microscopic View of Maxillary Anterior Teeth���������������������������������������  46 4.3.2 Microscopic View of Maxillary Posterior Teeth �������������������������������������  47 4.3.3 Microscopic View of the Mandibular Anterior Teeth �����������������������������  49 4.3.4 Microscopic View of the Mandibular Posterior Teeth�����������������������������  50 4.4 Thoughts and Comments Regarding the Practice of Micro Prosthodontics �������  51 4.4.1 Using a Microscope Can Prolong the Career Longevity of Dentists and Improve Clinical Results �����������������������������������������������  51 4.4.2 Microscopy Does Not Mean Minimal Invasiveness �������������������������������  52 4.4.3 Application of Dental Microscope in Prosthodontics Teaching �������������  53 4.4.4 “Five Difficulties” in the Practice and Teaching of Microscopic Prosthodontics�����������������������������������������������������������������������������������������  53 4.4.5 Consensus Should Be Achieved on Microscopic Prosthodontic Teaching���������������������������������������������������������������������������  56 4.5 Summary and Prospect ���������������������������������������������������������������������������������������  57 Suggested Readings �����������������������������������������������������������������������������������������������������  57 Part II Sequential and Key Clinical Techniques for Digital Micro Prosthodontics 5 Pain  Management and Comfortable Treatment in Micro Prosthodontics �����������  61 5.1 Local Anesthetics and Local Anesthesia Methods�����������������������������������������������  61 5.1.1 How to Choose Local Anesthetics�����������������������������������������������������������  61

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5.1.2 How to Choose Local Anesthesia Method�����������������������������������������������  62 5.1.3 How to Calculate Drug Dosage���������������������������������������������������������������  64 5.1.4 Sedation���������������������������������������������������������������������������������������������������  66 5.2 Clinical Operation Procedure�������������������������������������������������������������������������������  67 5.2.1 Evaluation and Preparation Before Anesthesia���������������������������������������  67 5.2.2 Implementation of Anesthesia�����������������������������������������������������������������  68 5.2.3 Complications �����������������������������������������������������������������������������������������  69 5.3 Pain Control of Tooth Preparation�����������������������������������������������������������������������  70 5.3.1 Principles and Mechanisms���������������������������������������������������������������������  70 5.3.2 Pain Control During and After Tooth Preparation�����������������������������������  72 5.4 Pain Control of Dental Implantation�������������������������������������������������������������������  72 5.4.1 Principles and Mechanisms���������������������������������������������������������������������  72 5.4.2 Reasons for Pain after Dental Implantation���������������������������������������������  73 5.4.3 Pain Control After Dental Implantation���������������������������������������������������  73 5.5 Summary and Prospect ���������������������������������������������������������������������������������������  74 Suggested Readings �����������������������������������������������������������������������������������������������������  74 6 Isolation  of the Operative Field in Micro Prosthodontics: Practical Rubber Dam Technology���������������������������������������������������������������������������  75 6.1 Rubber Dam and Accessories �����������������������������������������������������������������������������  75 6.1.1 Composition of Rubber Dam Kit�������������������������������������������������������������  75 6.2 Basic Technology of Rubber Dam�����������������������������������������������������������������������  77 6.2.1 Placement of Rubber Dam�����������������������������������������������������������������������  77 6.2.2 Reminder for Rubber Dam Placement�����������������������������������������������������  79 6.3 Use of Rubber Dam in Special Situations�����������������������������������������������������������  81 6.3.1 Gingival Sulcus Fluid or Saliva Microleakage ���������������������������������������  81 6.3.2 Large Defect of the Tooth or Poor Retention of the Crown���������������������  81 6.3.3 Isolation of PFM and Ceramic Crown�����������������������������������������������������  81 6.3.4 Isolation of Fixed Bridge Restoration�����������������������������������������������������  81 6.3.5 Tooth Neck Defect�����������������������������������������������������������������������������������  81 6.3.6 Patients in Poor General Condition and Elderly Patients �����������������������  81 6.4 Summary and Prospect ���������������������������������������������������������������������������������������  81 Suggested Readings �����������������������������������������������������������������������������������������������������  81 7 Introduction  to Digital Micro Tooth Preparation Technology �������������������������������  83 7.1 Control of Tooth Preparation Amount�����������������������������������������������������������������  83 7.1.1 Biological Factor�������������������������������������������������������������������������������������  84 7.1.2 Biochemical Factor ���������������������������������������������������������������������������������  85 7.1.3 Esthetic and Functional Factor of Prosthesis�������������������������������������������  86 7.2 Control of the Preparation Shape�������������������������������������������������������������������������  86 7.2.1 Requirements for the Shape of the Axial Surface of the Preparation �����  86 7.2.2 The Control of the Position and Shape of the Preparation’s Margin�������  87 7.3 Instrument Selection for Tooth Preparation���������������������������������������������������������  89 7.3.1 Types and Selection of Cutting Bur for Tooth Preparation���������������������  89 7.3.2 Types and Selection of Dental Handpiece and Motors ���������������������������  92 7.4 Application of TRS Guide in Tooth Preparation�������������������������������������������������  94 7.4.1 Classification According to the Purpose of Use���������������������������������������  94 7.4.2 Classification According to Manufacturing Technology�������������������������  95 7.5 Classification and Characteristics of the Existing Micro Tooth Preparation Techniques�����������������������������������������������������������������������������  96 7.5.1 Micro Groove Reference Tooth Preparation Technique��������������������������  96 7.5.2 Micro Hole Reference Tooth Preparation Technique�������������������������������  99 7.6 Clinical Workflow and Preparation Method of High-Precision Margin �������������  99 7.6.1 Three Determinations������������������������������������������������������������������������������ 100

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7.6.2 Three Choices ����������������������������������������������������������������������������������������� 101 7.6.3 Three Steps���������������������������������������������������������������������������������������������� 102 7.7 Summary and Prospect ��������������������������������������������������������������������������������������� 102 Suggested Readings ����������������������������������������������������������������������������������������������������� 102 8 Digital Impression Technology����������������������������������������������������������������������������������� 105 8.1 Classification and Characteristics of Digital Impression������������������������������������� 105 8.1.1 Classification of Digital Impression�������������������������������������������������������� 105 8.1.2 Characteristics of Digital Impression������������������������������������������������������ 108 8.2 Operation Procedure of Digital Intraoral Scanning System ������������������������������� 109 8.2.1 Installation of Digital Intraoral Scanning System����������������������������������� 109 8.2.2 Introduction to Home Page of Intraoral Scanning Software������������������� 109 8.2.3 Case Management in Intraoral Scanning Software��������������������������������� 109 8.2.4 Scanning Scheme and Scan and Image in Intraoral Scanning Software ��������������������������������������������������������������� 111 8.2.5 Processing of Digital Intraoral Scanning Model������������������������������������� 117 8.2.6 Storage and Export of Digital Intraoral Scanning Data��������������������������� 120 8.3 Common Problems and Solutions of Digital Impression ����������������������������������� 120 8.3.1 Common Problems and Solutions About Hardware ������������������������������� 120 8.3.2 Common Problems and Solutions About Software��������������������������������� 122 8.4 Summary and Prospect ��������������������������������������������������������������������������������������� 123 Suggested Readings ����������������������������������������������������������������������������������������������������� 123 9 Digital  Depth-Hole-Guiding Micro Tooth Preparation for Porcelain Veneer������� 125 9.1 Overview and Indications of Porcelain Veneer ��������������������������������������������������� 125 9.1.1 The Indications of Porcelain Veneer ������������������������������������������������������� 125 9.1.2 The Characteristics of Porcelain Veneer ������������������������������������������������� 125 9.1.3 Materials of Porcelain Veneer ����������������������������������������������������������������� 126 9.1.4 Types of Porcelain Veneer����������������������������������������������������������������������� 126 9.2 Design of Targeted Restorative Space (TRS) and Porcelain Veneer Preparation����������������������������������������������������������������������������������������������� 128 9.2.1 TRS Design of Porcelain Veneer������������������������������������������������������������� 128 9.2.2 Preparation Design of Porcelain Veneer ������������������������������������������������� 128 9.3 The Clinical Protocol of Micro Tooth Preparation with Digital Guide for Porcelain Veneer������������������������������������������������������������� 130 9.3.1 Veneer Preparation Using the Silicone Rubber Guide����������������������������� 130 9.3.2 Veneer Preparation Using the Transparent Vacuum-Formed TRS Guide������������������������������������������������������������������� 136 9.3.3 Veneer Preparation Using 3D Printing TRS Guide��������������������������������� 140 9.3.4 Finishing and Polishing��������������������������������������������������������������������������� 143 9.4 Gingival Retraction Technique Under a Microscope������������������������������������������� 143 9.4.1 Microscope Field of View for Gingival Retraction��������������������������������� 145 9.4.2 The Procedure of Gingival Retraction Under a Microscope������������������� 145 9.5 Impression Making and Provisional Restoration������������������������������������������������� 146 9.5.1 Impression Making ��������������������������������������������������������������������������������� 146 9.5.2 Provisional Restoration��������������������������������������������������������������������������� 146 9.6 Overview and Indications of Partial Porcelain Veneers��������������������������������������� 147 9.6.1 Indications and Contraindications of Partial Porcelain Veneer��������������� 147 9.6.2 Materials for Partial Porcelain Veneer����������������������������������������������������� 147 9.6.3 TRS Design for Partial Porcelain Veneer������������������������������������������������� 148 9.6.4 Preparation Requirements for Partial Porcelain Veneer��������������������������� 148 9.6.5 Preparations for Tooth Preparation of Partial Porcelain Veneer�������������� 148 9.6.6 Preparation of Various Types of Dental Veneers������������������������������������� 149 9.7 Summary and Prospect ��������������������������������������������������������������������������������������� 151 Suggested Readings ����������������������������������������������������������������������������������������������������� 151

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10 Digital  Micro Tooth Preparation for Posterior Indirect Adhesive Restorations������������������������������������������������������������������������������������������������ 153 10.1 Overview of Posterior Indirect Adhesive Restorations ������������������������������������� 153 10.1.1 The Advantages and Disadvantages of PIAR��������������������������������������� 153 10.1.2 Material Selection for PIAR����������������������������������������������������������������� 154 10.1.3 Types of PIAR��������������������������������������������������������������������������������������� 155 10.2 Preparation Design of Posterior Indirect Adhesive Restoration ����������������������� 155 10.2.1 The Amount of Preparation������������������������������������������������������������������� 155 10.2.2 The Principle of Posterior Indirect Adhesive Restoration Preparation������������������������������������������������������������������������� 156 10.3 Micro Preparation Protocol for Posterior Indirect Adhesive Restorations ������� 159 10.3.1 Basic Principles of PIAR Preparation��������������������������������������������������� 159 10.3.2 Preparation Before Tooth Preparation��������������������������������������������������� 159 10.3.3 Preparation Process of Micro Preparation Guided by TRS Guide������� 159 10.3.4 Preparation for Single-Surface PIAR��������������������������������������������������� 161 10.3.5 Preparation for MO/DO PIAR ������������������������������������������������������������� 162 10.4 Summary and Prospect ������������������������������������������������������������������������������������� 163 Suggested Readings ����������������������������������������������������������������������������������������������������� 164 11 Digital  Depth-Hole-Guiding Micro Preparation for All-Ceramic Crown������������� 165 11.1 Overview and Indications of All-­Ceramic Crown��������������������������������������������� 165 11.1.1 Indications of All-Ceramic Crown������������������������������������������������������� 165 11.1.2 Contraindications of All-Ceramic Crown��������������������������������������������� 166 11.2 Classification of All-Ceramic Material ������������������������������������������������������������� 166 11.2.1 Slip-Casting Ceramic ��������������������������������������������������������������������������� 166 11.2.2 Castable Glass Ceramic ����������������������������������������������������������������������� 166 11.2.3 Pressed Castable Ceramic��������������������������������������������������������������������� 167 11.2.4 Infiltrated Ceramic ������������������������������������������������������������������������������� 167 11.2.5 Machinable Ceramic����������������������������������������������������������������������������� 167 11.2.6 Zirconia Ceramic or Zirconia-­Toughened Ceramic ����������������������������� 167 11.2.7 Nanocomposite Ceramic����������������������������������������������������������������������� 168 11.2.8 Ceramic-Resin Composite ������������������������������������������������������������������� 168 11.3 The Clinical Protocol of Digital Depth-­Hole-­Guiding Micro Tooth Preparation for All-Ceramic Crown��������������������������������������������� 168 11.3.1 Analysis and Design Phase������������������������������������������������������������������� 168 11.3.2 Micro Tooth Preparation of Anterior Teeth Under the Guidance of the Transparent Vacuum-Formed TRS Guide����������������������������������������������������������������� 170 11.3.3 Micro Tooth Preparation of Anterior Teeth Under the Guidance of the 3D Printing TRS Guide of Non-uniform Thicknesses����������������������������������������������������������������� 173 11.3.4 Impression and Temporary Restoration ����������������������������������������������� 175 11.4 Summary and Prospect ������������������������������������������������������������������������������������� 177 Suggested Readings ����������������������������������������������������������������������������������������������������� 178 12 Immediate  Dentin Sealing and Micro Bonding������������������������������������������������������� 179 12.1 Overview and Mechanism of Adhesion������������������������������������������������������������� 179 12.1.1 Concept of Adhesive����������������������������������������������������������������������������� 179 12.1.2 Mechanism of Adhesion����������������������������������������������������������������������� 179 12.1.3 Type of Adhesives��������������������������������������������������������������������������������� 180 12.1.4 Bonding of Enamel������������������������������������������������������������������������������� 181 12.1.5 Bonding of Dentin��������������������������������������������������������������������������������� 182 12.1.6 Immediate Dentin Sealing (IDS) ��������������������������������������������������������� 184 12.1.7 The Treatments of the Ceramic Prosthesis������������������������������������������� 185

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12.1.8 Cementing of Temporary Restorations������������������������������������������������� 187 12.2 Micro Bonding Process of Zirconia- and Glass-Based Ceramics��������������������� 188 12.2.1 Characteristics of Bonding of Different Restorative Materials������������� 188 12.2.2 Surface Conditioning of Different Restorative Materials��������������������� 189 12.2.3 Surface Conditioning of the Preparation (Abutment Tooth) Which Is to Be Repaired with Different Restorative Materials����������������������������������������������������� 190 12.3 Micro Bonding Process of Porcelain Veneer����������������������������������������������������� 192 12.3.1 Selection of Adhesive Resin����������������������������������������������������������������� 192 12.3.2 Try-In and Preparation ������������������������������������������������������������������������� 192 12.3.3 Surface Conditioning of the Tooth������������������������������������������������������� 193 12.3.4 Surface Conditioning of the Porcelain Veneer ������������������������������������� 195 12.3.5 Placement��������������������������������������������������������������������������������������������� 196 12.3.6 Occlusal Check and Adjustment����������������������������������������������������������� 198 12.4 Micro Bonding Process of All-Ceramic Crown������������������������������������������������� 199 12.4.1 Selection of Adhesive��������������������������������������������������������������������������� 199 12.4.2 Try-In and Preparation ������������������������������������������������������������������������� 199 12.4.3 Occlusal Check and Adjustment����������������������������������������������������������� 199 12.4.4 Surface Conditioning of the Tooth Surface������������������������������������������� 199 12.4.5 Surface Conditioning of the All-Ceramic Crown��������������������������������� 201 12.4.6 Placement��������������������������������������������������������������������������������������������� 203 12.5 Summary and Prospect ������������������������������������������������������������������������������������� 204 Suggested Readings ����������������������������������������������������������������������������������������������������� 206 Part III Complications and Treatment After Micro-prosthodontics 13 Complications  and Treatment After Micro Prosthodontics ����������������������������������� 209 13.1 Routine Maintenance����������������������������������������������������������������������������������������� 209 13.1.1 Brush Teeth and Use Dental Floss Correctly ��������������������������������������� 209 13.1.2 Receive Regular Scaling and Treatment in Time If There Is Any Problem ��������������������������������������������������������� 209 13.1.3 Apply Fluoride and Prevent Secondary Caries������������������������������������� 209 13.2 Complications and Treatment ��������������������������������������������������������������������������� 209 13.2.1 Chipping Fracture of Porcelain������������������������������������������������������������� 209 13.2.2 Porcelain Cracking������������������������������������������������������������������������������� 210 13.2.3 Debonding of Prosthesis����������������������������������������������������������������������� 211 13.2.4 Dental Allergy��������������������������������������������������������������������������������������� 211 13.2.5 Abutment Fracture ������������������������������������������������������������������������������� 211 13.2.6 Discoloration at the Margin of the Prosthesis��������������������������������������� 211 13.2.7 Dental Pulp Devitalization and Secondary Caries ������������������������������� 212 13.3 Summary and Prospect ������������������������������������������������������������������������������������� 212 Suggested Readings ����������������������������������������������������������������������������������������������������� 212 Part IV Clinical Rehabilitation of Secondary Aesthetic Porcelain Restoration 14 Decisions  on Clinical Rehabilitation of Secondary Aesthetic Porcelain Restoration��������������������������������������������������������������������������������� 215 14.1 Possible Complications of Secondary Aesthetic Porcelain Restoration ����������� 215 14.1.1 Hypersensitivity of Abutment Teeth����������������������������������������������������� 215 14.1.2 Spontaneous Pain of Abutment Teeth��������������������������������������������������� 215 14.1.3 Loosening, Cracking and Discolouration of Abutment Teeth��������������� 216 14.1.4 Occurrence of Exacerbation of Periodontal Disease ��������������������������� 216

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14.1.5 Discolouration of Restoration��������������������������������������������������������������� 216 14.1.6 Loosening and Falling Off of Restoration ������������������������������������������� 216 14.1.7 Cracking, Breaking and Perforation of Restoration����������������������������� 216 14.1.8 Dysfunction and Psychological Problems ������������������������������������������� 217 14.2 Clinical Decision Tree of Secondary Aesthetic Porcelain Restoration Guided by TRS Guide ������������������������������������������������������������������� 217 14.2.1 Psychological Evaluation��������������������������������������������������������������������� 217 14.2.2 Previous Treatment Evaluation������������������������������������������������������������� 218 14.2.3 Prosthodontic Decision After Removing the Old Restoration������������������������������������������������������������������������������� 219 14.3 Typical Cases of Secondary Porcelain Aesthetic Repair and Retreatment ������� 220 14.3.1 Secondary Aesthetic Porcelain Restorations in the Anterior Area������� 220 14.4 Summary and Prospect ������������������������������������������������������������������������������������� 272 Suggested Readings ����������������������������������������������������������������������������������������������������� 274 15 Occlusal  Reconstruction Under the Guidance of Target Restorative Space��������� 275 15.1 Comprehensive Assessment Before Occlusal Reconstruction��������������������������� 275 15.1.1 Clinical Consultation and Risk Assessment����������������������������������������� 275 15.1.2 Examination of the Oral and Maxillofacial System����������������������������� 275 15.1.3 Radiographic Examination������������������������������������������������������������������� 277 15.1.4 Mounting of Diagnosis Casts onto the Articulator������������������������������� 277 15.2 Typical Cases of Occlusion Reconstruction Aided by the TRS Guide ������������� 277 15.2.1 A Case of Secondary Aesthetic and Functional Porcelain Restoration of Maxillae and Mandible Aided by TRS Guide��������������������������������������������������������������������������������������� 278 15.2.2 A Case of Secondary Aesthetic Porcelain Restoration of Maxillae and Mandible Aided by TRS Guide ��������������������������������� 285 15.2.3 A Case of Occlusal Reconstruction Restored by Implant-Supported Fixed Prosthesis with the Aid of Whole-­Process Digital Guidance����������������������������������������� 300 15.3 Clinical Application of Occlusion Adjusting Guide in Occlusal Reconstruction ������������������������������������������������������������������������������� 317 15.3.1 Digital Clinical Workflow of Occlusion Reconstruction for Cases with Insufficient Occlusal Space������������������������������������������� 318 15.3.2 A Clinical Case of Designing Occlusion Adjusting Guide������������������� 322 15.4 Summary and Prospect ������������������������������������������������������������������������������������� 334 Suggested Readings ����������������������������������������������������������������������������������������������������� 334 16 Cases  of Digital Micro Prosthodontics Guided by Target Restorative Space������� 337 16.1 Typical Cases of Digital Micro Restoration Guided by Wax-Up Surface��������� 337 16.1.1 A Case of Crown Lengthening Combining with Porcelain Veneer Restoration of Maxillary Anterior Tooth Guided by Mock-Up Surface��������������������������������������� 337 16.2 Typical Cases of Digital Micro Restoration Guided by Silicone Index������������� 344 16.2.1 A Case of All-Ceramic Crown of Maxillary Anterior Tooth with ETRS Guided by Silicone Index ��������������������������������������� 344 16.3 Typical Cases of Digital Micro Restoration Aided by Transparent Dental Membrane TRS Guide��������������������������������������������������� 347 16.3.1 A Case of Digital Micro Restoration of Traumatic Maxillary Anterior Tooth with Ceramic Veneer Aided by Transparent Dental Membrane TRS Guide ������������������������������������������������������������������������� 347

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16.3.2 A Case of Porcelain Inlay Restoration of Elongated and Rotated Maxillary Anterior Teeth Aided by Transparent Dental Membrane TRS Guide������������������������������������� 359 16.3.3 A Case of Porcelain Inlay Restoration of Defected Upper Anterior Teeth Aided by Transparent Dental Membrane TRS Guide ������������������������������������������������������������������������� 369 16.3.4 A Case of Porcelain Veneer Restoration of Maxillary and Mandibular Tetracycline Teeth Aided by Transparent Dental Membrane TRS Guide����������������� 381 16.4 Typical Cases of Digital Micro Restoration Aided by 3D Printing TRS Guide with Uniform Thickness����������������������������������������� 393 16.4.1 A Case of Digital All-Ceramic Restorations of Maxillary and Mandibular Anterior Tooth with Exogenous Severe Erosion and Extensive Caries Aided by 3D Printing TRS Guide with Uniform Thickness����������������� 393 16.5 Typical Cases of Digital Micro Restoration Aided by 3D Printing TRS Guide with Non-uniform Thickness��������������������������������� 410 16.5.1 A Case of Digital All-Ceramic Crown of Maxillary Rotated Anterior Tooth Aided by 3D Printing TRS Guide with Non-uniform Thickness ������������������� 410 16.5.2 A Case of Digital All-Ceramic Veneer of Maxillary Anterior Dental Fluorosis Aided by 3D Printing TRS Guide with Non-uniform Thickness ������������������� 417 16.5.3 A Case of Immediate Restoration of Prefabricated Crown Aided by 3D Printing TRS Guide with Non-uniform Thickness ��������������������������������������������������������������� 427 16.6 Typical Cases of Digital Micro Restoration Aided by Two-in-One TRS Guide for Implant Surgery and Tooth Preparation����������� 436 16.6.1 A Case of Digital Micro Restoration Aided by Two-in-One TRS Guide for Implant Surgery and Tooth Preparation��������������������������������������������������������������������������� 436 16.7 Summary and Prospect ������������������������������������������������������������������������������������� 452 Suggested Readings ����������������������������������������������������������������������������������������������������� 452

Authors and Contributors

About the Author Haiyang  Yu  received his Ph.D. in 1997 from the West China University of Medical Sciences (currently the West China Medical Center, Sichuan University, China) and undertook his postdoctoral research about The Mechanism of Fretting Damages in the Screw Structures of Dental Implants from 2002 to 2006 in Tribology Institute, Southwest Jiaotong University, China. He completed the Summer Institute in Clinical Dental Research Methods held by the School of Dentistry in the University of Washington in 2009 and the course entitled Academic Medicine held at St Edmund Hall in the University of Oxford in 2016. He did his research on The Mechanism of Osseous Integration at the Bone-implant Interface under Metabolic Diseases in Pharmacology and Toxicology with the Higuchi Biosciences Center at the University of Kansas as a visiting scholar from 2011 to 2012. Dr. Yu has worked in West China Hospital/School of Stomatology, Sichuan University since 1997 to present. In 2003, he was appointed as an associate professor after being in service as a lecturer for 6 years and then was appointed as a professor in 2005. He has served as the director of Stomatology Technology Department since 2004 and the chair of the Department of Prosthodontics II since 2010 at the West China Hospital of Stomatology. He was the deputy dean of the West China School of Stomatology from 2011 to 2017. Dr. Yu is currently the president of Prosthodontics Committee of Chinese Stomatological Association and a fellow of the International College of Dentists. He is also the deputy editor of the West China Journal of Stomatology and Bone Research Journal. His main research areas are in esthetic micro-­prosthodontics, digital dental implant restoration, and digital design and processing of dental prosthesis. He has published more than 200 articles and authored the textbooks Fixed Prosthodontics (People’s Medical Publishing House, 2016), Aesthetics in Stomatology (People’s Medical Publishing House, 2015) as well as other more than 30 books. His research achievement was awarded the first prize of Natural Science of the Ministry of Education of China, and his teaching achievement was awarded the second prize of Teaching Achievement of the Ministry of Education of China. Dr. Yu owns 87 patents and has exploited and translated 13 of them into application, including HX-6 Depth Cutting Scaled Bur Kit, Measuring-and-Guiding Kit for Implant, etc. He has invented the depth-hole-guiding tooth preparation technique, accurate physical measuring technique for implantation, TRS tooth preparation guide, depth control guide for laminate veneers, dental resin injection guide, iTRS interoperative measuring implant guide, etc.

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Contributors Duanjing Chen, DDS, MS, PhD  State Key Laboratory of Oral Diseases, National Clinical Research Center for Oral Diseases, West China Hospital of Stomatology, Sichuan University, Chengdu, China Bo Dong, DDS, CDT  Department of Dental Technology, West China Hospital of Stomatology, Sichuan University, Chengdu, China Lin Fan, DDS, MS  State Key Laboratory of Oral Diseases, National Clinical Research Center for Oral Diseases, West China Hospital of Stomatology, Sichuan University, Chengdu, China Jing Gao, DDS, MS, PhD  State Key Laboratory of Oral Diseases, National Clinical Research Center for Oral Diseases, West China Hospital of Stomatology, Sichuan University, Chengdu, China Jinxiu  He, DDS, MS  State Key Laboratory of Oral Diseases, National Clinical Research Center for Oral Diseases, West China Hospital of Stomatology, Sichuan University, Chengdu, China Yutian Huang, DDS, MS  State Key Laboratory of Oral Diseases, National Clinical Research Center for Oral Diseases, West China Hospital of Stomatology, Sichuan University, Chengdu, China Juying Li, DDS, MS, PhD  State Key Laboratory of Oral Diseases, National Clinical Research Center for Oral Diseases, West China Hospital of Stomatology, Sichuan University, Chengdu, China Yiyuan Li, DDS, MS, PhD  State Key Laboratory of Oral Diseases, National Clinical Research Center for Oral Diseases, West China Hospital of Stomatology, Sichuan University, Chengdu, China Chunxu  Liu, DDS, MS, CDT  Department of Dental Technology, West China Hospital of Stomatology, Sichuan University, Chengdu, China Jiayi  Lu, DDS, MS State Key Laboratory of Oral Diseases, National Clinical Research Center for Oral Diseases, West China Hospital of Stomatology, Sichuan University, Chengdu, China Yuqing Lu, DDS, MS  Department of Dental Technology, West China Hospital of Stomatology, Sichuan University, Chengdu, China Tian Luo, DDS, MS, PhD  State Key Laboratory of Oral Diseases, National Clinical Research Center for Oral Diseases, West China Hospital of Stomatology, Sichuan University, Chengdu, China Ziyu  Mei, DDS, MS, CDT Department of Dental Technology, West China Hospital of Stomatology, Sichuan University, Chengdu, China Wei Ren, DDS, CDT  Department of Dental Technology, West China Hospital of Stomatology, Sichuan University, Chengdu, China Meijie  Wang, DDS, MS, PhD State Key Laboratory of Oral Diseases, National Clinical Research Center for Oral Diseases, West China Hospital of Stomatology, Sichuan University, Chengdu, China Xingqiang  Yang, DDS, CDT Department of Dental Technology, West China Hospital of Stomatology, Sichuan University, Chengdu, China

Authors and Contributors

Authors and Contributors

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Li Yue, MDT, CDT  Department of Dental Technology, West China Hospital of Stomatology, Sichuan University, Chengdu, China Jiayi  Yu, DDS, MS, CDT Department of Dental Technology, West China Hospital of Stomatology, Sichuan University, Chengdu, China Yuqiang Zhang, DDS, MS  State Key Laboratory of Oral Diseases, National Clinical Research Center for Oral Diseases, West China Hospital of Stomatology, Sichuan University, Chengdu, China Yuwei  Zhao, DDS, MS, PhD State Key Laboratory of Oral Diseases, National Clinical Research Center for Oral Diseases, West China Hospital of Stomatology, Sichuan University, Chengdu, China

1

Overview

With the progress of science and technology, we have uncon- 1. The traditional clinical experience of prosthodontics is sciously entered the age of information and digitalization, mostly obtained with the naked eye, which is difficult to and various disciplines of dentistry including prosthodontics match with MIPP (minimally invasive prosthetic procehave also achieved unprecedented rapid development. dures) and MICP (minimally invasive cosmetic dentistry) Having newly representative dental materials like high-­ in essence. Clinicians need to see fine things clearly. translucent zirconia, PEEK, and PEKK successfully applied Therefore, it is necessary to upgrade the visual basis of in dental clinical practice, we have been able to achieve the clinical prosthodontics from naked-eye view to magnified real digitalization from design, tooth preparation, to prostheor microscopic vision. sis manufacturing and make virtual design and solid fabrica- 2. There is no consensus on numerical requirements and tion almost the same. All kinds of digital technology have quantitative relations, and the authenticity of these figures liberated the physical body and are liberating the mentality; needs to be verified. Although prosthodontics and dental therefore, we are entering a more efficient digital age! implantology have various numerical requirements for But we have to admit the current situation that prosthrestorative space, tooth preparation amount, prosthesis, odontics has always been a clinical science based on experiimplant site, and occlusal adjustment, they lack accurate ence. For example, the two most representative invasive measuring method and don’t clarify the measuring plane, operations, tooth preparation and placing implants, are starting point, and end point of measuring. In terms of mainly implemented freehand and with visual inspection at clinical workflow, there are no accurate quantitative relapresent, significantly characterized by empiricism. On the tions and transfer methods available for clinical steps. other hand, we have to realize that currently the widely used The lack or inaccuracy and incompleteness of these preand mature digital technology of dentistry is mainly about cise transfer methods of quantitative relations hinder the prosthesis manufacturing. Such digitalization that limits to further development of digital prosthodontics charactermanufacturing end while clinical end is based on experience ized by efficiency, accuracy, and minimal invasiveness. In can’t support the realization of digital prosthodontics. In the short, we lack the theoretical understanding of restorative face of opportunities and challenges, the key to upgrading space and corresponding clinical technology based on the clinical end of prosthodontics from experience guidance quantitative relations and involved in clinical production to digital guidance is to invent a series of clinical techniques of restoration. relying on digital guidance instead of experience which is an At present, there is no consensus about the definition important foundation to support the development of real digof micro prosthodontics at home and abroad. We think ital prosthodontics in the future. that micro prosthodontics refers to the technology that In the future, the greater development of prosthodontics uses microscope as a diagnosis, treatment, and visual aid must rely on the complete digitalization and informatization tool to carry out direct or indirect restorative operation. of the clinical workflow, and it is an urgent task to improve Compared with the restorative process with the naked clinicians’ understanding about digital clinical end. eyes, it is easier to achieve the goal of minimally invasive Otherwise the complete digitalization is impossible to realoperation. Similar to the micro root canal diagnosis and ize, let alone the accurate, efficient, and minimally invasive treatment, micro prosthodontics also relies on the microprosthodontics. In order to construct the clinical end of scope to improve the quality of tooth preparation, bondprosthodontics based on digital science, we must solve the ing and other operations, and to obtain a more stable and following two critical problems and challenges: long-term final effect. The goal of micro prosthodontics

© Springer Nature Singapore Pte Ltd. and People’s Medical Publishing House 2022 H. Yu, Digital Guided Micro Prosthodontics, https://doi.org/10.1007/978-981-19-0256-7_1

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1 Overview

is precision and minimal invasiveness. The concept, operation position and operation equipment of micro ­ prosthodontics are different from those of traditional prosthodontics. Micro prosthodontics doesn’t simply mean using naked-eye prosthodontic techniques under the microscope, because many of the prosthodontic techniques under the naked eye is not suitable for operating under the microscope and many micro prosthodontic techniques are not from naked-eye prosthodontics. Therefore, generally speaking, all kinds of prosthodontic techniques can be used under the microscope, and the micro prosthodontics refers to the special techniques suitable for the use under the microscope which can be the classic prosthodontic techniques and more importantly new techniques just for micro prosthodontics. In the face of these historical opportunities and challenges, this book focuses on digital micro prosthodontics and provides some thoughts about digital guidance and micro prosthodontics. We are hoping experience-oriented prosthodontics can be improved to digitally guided prosthodontics!

1.1 Development and Requirements of Micro Dentistry 1.1.1 Different Levels of Visual Basis Bring Different Levels of Recognition As we all know, the birth and development of astronomy has always been closely related to the emergence and development of telescopes. In ancient times, people could only look up at the stars with the naked eyes and observe some simple astronomical phenomena, which resulted in many wonderful Chinese myths such as Goddess Chang’e flying to the moon and Tiangou eating the moon. However, there are also scientific records about astronomy: in the early Zhou Dynasty, gnomon was invented to measure time; in the Ming Dynasty, armillary sphere appeared and was used to measure the coordinate position of celestial objects; and in the second half of the sixteenth century, quadrant was invented to measure the angular distance between celestial objects and the horizontal plane. In the west, before the emergence of telescopes, proponents of the geocentric theory and those of the heliocentric theory had been debating for a long time. In the second century A.D., Ptolemy put forward the geocentric theory, which was later adopted by the church and became one of the theoretical bases of the idea that God created the world; in 1543, Copernicus proposed the heliocentric theory in the book De Revolutionibus Orbium Coelestium (On the Revolutions of the Heavenly Spheres); and in the sixteenth to seventeenth centuries, Bruno insisted on promoting the heliocentric theory and was burned to death in Rome by the church, and

Kepler proved and developed Copernicus’s theory. Although the ancients have tried their best to explain nature by using all kinds of methods and techniques and proposed many theories, the phenomena observed with the naked eye and the analysis precision are limited. Most of them can only observe some superficial features and positions of celestial objects, having no advanced techniques to know more details, forms, and properties of celestial objects. Under such circumstances, it’s difficult for astronomy to advance greatly. In 1609, as the inventor of astronomical telescope in human history, Galileo was the first person who used astronomical telescope to observe the sky for a long time. His observation results were revolutionary, confirming the fact that the earth rotated around the sun, thus triggering a great revolution in the history of astronomy. Galileo was undoubtedly the pioneer of modern physics. The invention of optical telescopes has greatly improved the observation quality. Through telescopes, mountains and holes on the surface of the moon and satellites of Jupiter were discovered, and even the basic form of the universe was confirmed, making ancient astronomy enter the stage of modern astronomy. However, the precision and magnification of the optical telescope was still limited, and only visible light could be seen through it which was prone to electromagnetic interference. With the rapid development of modern astronomy, observation instruments have been greatly improved. The typical representatives are radio telescopes (China FAST, 2016) and space telescopes (Spitzer, 2003). Discoveries which are called Four great inventions in astronomy have been made: cosmic microwave background radiation, pulsar, quasar, and interstellar organic molecules. In addition to visible light, ultraviolet, infrared, radio wave, X-ray, and gamma ray of celestial objects can be observed now. Based on the new astronomical telescope, astronomy has entered a new stage. The development of the currently hot discipline, biology, is closely related to the progress of observation instruments. Before the invention of optical microscope, biology was in the stage of macrobiology. Generally, the resolution of the naked eye of normal people is about 0.2 mm, and the details of things that can be observed are limited, so naked-eye biology could only be restricted at the level of tissue. In 1543, the Flemish anatomist and physician, Andreas Vesalius, published the book De Humani Corporis Fabrica (On the Fabric of the Human Body) which revealed the structure of the human body at the organ level. In 1665, Robert Hooke, a British scientist, observed the tiny plant cork tissue with a microscope for the first time and found and named microscopic honeycomb cavities as cell. Microscope offered better and more micro research means for microbiology and was rapidly and widely used in the diagnosis and treatment in clinical medicine. In 1949, the first electron microscope image of cell was obtained. The appearance of electron microscope marks that biological research has entered the

1.2  Application of Dental Microscope in Dental Specialties

field of submicroscopic structure where people can see nuclear membrane, nucleolus, chromosome, mitochondria, centrosome, Golgi body, matrix, and so on. Now, the invention of STM (scanning tunneling microscope) and SPM (scanning probe microscopy) allows the observation to reach the molecular level, which can provide high-resolution images of biomolecules and observe the interaction of biomolecules. Therefore, the old proverb “seeing is believing” is not necessarily true. We can’t stop at the naked-eye observation as the more micro visual scale corresponds to the higher-­ level cognitions!

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And micro root canal therapy was listed as a compulsory course of US dental colleges 30 years ago.

1.2 Application of Dental Microscope in Dental Specialties 1.2.1 Accuracy of Measurement Required by Each Dental Specialty Is Not the Same, and that of Endodontics and Prosthodontics Is Relatively Small

Dentistry is a branch of medicine concerned with the diagnosis, prevention, and treatment of oral diseases and discom1.1.2 Development of Micro Dentistry fort. It generally deals with diseases of dentition and also involves oral mucosa and neighboring related structures and In the past century, clinical dentistry has been pursuing more tissues, especially the maxillofacial region. Dentistry often minimally invasive, more predictable and better treatment involves the location and measurement of anatomical physieffects. For more than 10 years, in order to obtain a long-­ ological structure. And the intervention brought by treatment term, stable and effective clinical prognosis, micro dentistry will change the shape and position of physiological struchas been accepted by more and more dentists in China. The ture. Each dental specialty has its own requirement about pre-restorative examination, diagnosis, and treatment are all accuracy of measurement. In orthodontics and orthognathic developing toward a more microscopic, refined and pre- surgery, measurements are made of specific landmarks on served direction, and the realization of “see earlier and more radiographs taken by the X-ray or CBCT.  Distances and minor” idea relies on the popularization and application of angles between these landmarks are measured and analyzed microscopic technology in clinical dentistry. so as to understand the structure characteristics, interrelaSince the 1980s, micro dentistry has developed rapidly. In tion, and variation of the soft and hard tissues in the cranio1978, Dr. Apotheker and Dr. Jako of the United States intro- facial region. The measurement is usually accurate to 1 mm. duced the concept of operating microscope into dentistry for In periodontics, the most common measuring tool in dental the first time and believed that operating microscope could practice, periodontal probe, is usually used to measure the effectively improve the visual sensitivity, which greatly gingival soft tissue, recording the anatomical position and boosted the development of the diagnosis and treatment of guiding the scope of operation. The accuracy of measureendodontic diseases. In 1981, the first dental operating ment is the minimum scale of periodontal probe, that is, microscope was invented. In the late 1980s, Dr. Carr, an 1  mm (Fig.  1.1). In endodontics and prosthodontics, the endodontist, promoted the application of dental operating focus is usually the tooth structure and the dental pulp. As microscope in apical surgery. In January 1998, the American the residual dentin thickness of less than 0.5 mm after tooth Dental Association (ADA) stipulated that all endodontic courses approved by ADA must involve the use of dental microscope in endodontic treatment. At that time, the practical value of dental operating microscope began to be more widely recognized by international dental experts and clinicians. Since then, the use of this new medical technology, that is, operating microscope, has expanded from endodontics to periodontics, prosthodontics, oral and maxillofacial surgery, and plastic surgery. The introduction of operating microscope into dentistry has become one of the most important breakthroughs in the development of contemporary dentistry. Its significance lies in the upgrading of dental clinical practice from traditional naked-eye macro-operation to more precise and accurate micro operation. At present, this technology has been widely used in European and American countries. It is reported that half of the 160,000 dentists in Fig. 1.1  The most common measuring tool with 1  mm accuracy in the United States are using microscope in clinical practice. clinical dentistry—periodontal probe

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preparation may cause severe pulpal reaction, more minimally invasive tooth preparation is necessary to preserve more tooth structure and protect the pulp vitality. And the margin width required by the minimally invasive porcelain veneer is as small as 0.1–0.3  mm. Therefore, the accuracy required by these two dental specialties is far less than 1 mm, with a minimum of 0.1 mm, usually 0.3–0.5 mm. The accuracy of measurement by periodontal probe is far from effective.

1.2.2 The Application of Microscope in Endodontics Endodontics is the first dental specialty that microscope is widely used in. Cavity filling and root canal treatment are the main clinical operations in endodontics. Because of the small size and special anatomy of the root canal, it is difficult for dentists to obtain a good vision in the canal. The determination about whether the root canal filling is in place or not often depends on hand feeling and experience, which is a typical experience-oriented dental treatment. However, the introduction of dental microscope provides a good field of vision for dentists and significantly reduces the probability of failure to identify root canal and improves the accuracy of removing calcification and detecting root canal orifices, allowing the successful location, opening, and preparation of blocked root canal under complex circumstances. Microscopes and accessories have great advantages in root canal retreatment, removal of broken instruments and repair of perforated pulp cavity, and have achieved good and reliable results of diagnosis and treatment.

1.2.3 The Application of Microscope in Periodontics and Dental Implantology The use of microscope brings more clear vision for periodontists and makes the operation more accurate. The magnifying effect and superior illumination favor the dentists’ recognition of subgingival tissue and judgment of periodontal pocket tissue, so that the flap can be at the optimal position and the wound can be Class I wound. The precision of implantation site in dental implant surgery is very important. In the aesthetic area, placing the implant at the over-buccal and over-deep site usually results in the bone absorption three times more than that at the optimal implant site and has high incidence of postoperative complications. The average accuracy of digital surgical guide is at millimeter level, leading to more accurate implant site which is the guarantee of the final restorative effect. Some people think that dental

1 Overview

magnifying loupe can meet the requirements of periodontics and dental implantology regarding accuracy which is at millimeter level.

1.2.4 The Application of Microscope in Prosthodontics Although currently restorative operations under a microscope, which is mainly used in aesthetic prosthodontics, are not so popular and still lack universally acknowledged theory and supporting practical techniques, the introduction of microscope and its accessories and clinical techniques for repair treatment will undoubtedly improve the restorative effect. First of all, the excellent illumination and magnification improvement of vision field by magnification makes it easy to distinguish caries, tooth structure, resin, and porcelain which are hard to distinguish under the traditional working conditions and allows operators to see the details that could not be observed in the past. Secondly, caries removal, cavity preparation, direct restoration, and tooth preparation can be performed more minimally invasively and accurately. Under a microscope, the gingival retraction cord can be placed precisely and lightly, and checking of margin sealing and removal of the adhesive after bonding can be carried out more easily. The 0.1–0.3 mm accuracy of margin width and tooth preparation amount has already exceeded the limit of ordinary human eyes and can hardly be achieved without the help of microscope, special burs, and other special instruments.

1.2.5 The Application of Microscope in Dental Technology By using the microscope in the lab, the dental technician can check the integrity of the impression more accurately and find out whether there is a small overhang on the edge of the prosthesis, whether the thickness and length of the edge are appropriate, and whether there is a vulnerable area. The use of microscope in dental technology has greatly improved the precision and quality of prosthesis and has a promising prospect. At present, the use of desktop magnifier or head-­ mounted magnifying loupe with low magnification is common, but the fabrication of restoration under the microscope is rare. It should be pointed out that the use of microscope merely the in clinical end, not in the manufacturing end, would hardly produce the accurate and minimally invasive restoration. Only by applying the microscope into the whole process from the clinical end to the manufacturing end can accurate prosthodontics be realized.

1.3  Development and Advantages of Micro Prosthodontics

1.2.6 The Application of Microscope in Teaching, Scientific Research, and Clinical Skill Training The microscope is more and more widely used in the teaching and scientific research of various dental specialties, serving as a more vivid method of teaching and researching. Some microscopes equipped with assistant lens or digital imaging system allow students to observe the details and key points of the operation under the microscope in real time, which is favorable for improving the quality of clinical teaching. Some microscopes equipped with cameras can not only allow recording the representative steps and important anatomical landmarks in the operation process but also be used after operation for reviewing and even clinical research and training, etc., which is beneficial for comprehensively improving the teaching and research quality of dentistry.

5 Table 1.1  Common complications and causes Common complications Abutment tooth pain

Direct causes Perforation of pulp cavity Dentin exposure Adhesive irritation

Gingival recession and inflammation

Gingival injury, violation of biological width, poor oral hygiene

Prosthesis fracture

The thickness of the restoration is less than the minimum value required by the material strength

Prosthesis debonding

Insufficient retention Improper bonding Occlusion factors

1.3 Development and Advantages of Micro Prosthodontics In order to better understand the development and advantages of micro prosthodontics, let’s firstly review the problems of prosthodontics in the naked-eye age.

1.3.1 In the Naked-Eye Age, the Complications of Restoration Are Mostly Related to Unclear Vision The traditional restorative operation with the naked eyes can’t precisely control the amount and milling shape of tooth preparation and can’t ensure that the irreversible reduction and adjustment of natural teeth and restoration are performed according to the occlusal marks. The following complications often occur to the prepared teeth or restorations: abutment tooth pain, gingival recession and inflammation, prosthesis fracture, or prosthesis debonding. The specific causes are presented in Table 1.1. In fact, most of these complications are related to the unclear vision of the operator.

1.3.2 Reasons Why We Need Micro Prosthodontics For fixed restoration, esthetic restoration, and minimally invasive restoration, dental operating microscope can not only offer magnification and illumination system which can meet the needs of each stage of repair treatment but

Restorative causes of naked-eye repair Operation vision is not clear enough There is no design plan before tooth preparation and precise measurement and control during operation Improper selection of adhesive Operation vision is not clear enough, and traditional TP techniques can’t precisely control shape, position, and fitness of the margin The tooth preparation amount is not designed well before operation and is not precisely controlled during the naked-eye operation Improper occlusal design and inaccurate occlusal adjustment No design or unreasonable design before tooth preparation Improper surface conditioning of teeth Improper occlusal design and inaccurate occlusal adjustment

also record critical information by pictures or videos when being equipped with cameras, allowing postoperative analysis. The micro restoration technique was introduced in China in 1999, but due to the restriction of domestic economy and small demand of the public at that time, this technology was not very popular. With the rapid development of the dental industry in China, promising prospects of applications and large market space for micro dental technology which has great application prospects and market space, we have already owned original micro restoration techniques, such as micro depth-hole-guiding tooth preparation technique and TRS guiding technique, but we are still behind with respect to international advanced level, having problems like lack of auxiliary equipment, lack of guidance for operation and procedure of micro restoration, and insufficient popularization of these techniques in local clinics. Compared with the conventional prosthodontics with the naked eye, micro prosthodontics has these following advantages:

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1. Better visual field The microscope can provide a magnification of 3–20×, which enables dentists to recognize subtle tooth structure and perform accurate operation in clinical diagnosis and treatment. The field of vision under high magnification can be used for preparing accurate margin and checking the position and shape of the margin, checking the placement of the prosthesis, and removing excessive adhesives. The microscope also has better illumination system. The head-mounted magnifying loupe or desktop microscopes provide coaxial light source when working. Compared with the dental chair light, the illumination system of the microscope can eliminate all the blind spots in the field of vision and avoid the adverse effects of shadows caused by the inconsistency between the light source direction and the doctor’s field of vision. 2. Advanced ergonomics The dental microscope not only offers good vision but also enables dentists to perform operations with a relaxed posture, which can prevent the occurrence of various high-risk musculoskeletal cumulative diseases and other occupational diseases caused by the dental treatment operation. 3. Better implementation of precise tooth preparation Before performing tooth preparation, the design of tooth preparation amount should be completed. The micro depth-hole guiding tooth preparation can be accurate to 0.1  mm with the guidance of TRS guide. Therefore, only  relying on the magnified field of vision of the microscope can the tooth preparation be precisely implemented.

1 Overview

ments of patients but also comprehensively takes the psychological and physiological health of patients into consideration, which is in the best interests of patients. Microscope can provide a good and clear vision for minimally invasive clinical operation, but minimal invasiveness is a more complex and profound principle. Fixed prosthesis such as crown, bridge and veneer has appeared for nearly a 100 years, which are the main methods of aesthetic restoration. As crown, bridge, veneer and other fixed restorations are widely used in clinical practice, how to achieve accurate and minimally invasive tooth preparation has become the goal of dentists. At present, tooth preparation has become a routine technique that every clinician must master. The goal and essence of tooth preparation is to obtain accurate targeted restorative space (TRS) that is suitable for the selected restorative materials and manufacturing process. Meanwhile, the tooth preparation is affected by the biological safety, strength, appearance, and function of the prosthesis. Microscopes and accessories are only a means of implementation and auxiliary technology in the process of minimally invasive restoration. With the progress and development of dental materials, the thickness required for the strength of the prosthesis is becoming smaller and smaller, which provides the possibility for the preservation of more dental tissues. The minimum thickness of the prosthesis is 0.1–0.3  mm, and the repair accuracy is 0.1  mm. Only by using TRS guide and depth-­ hole-­guiding tooth preparation technique under the microscope can the operation accuracy be controlled at the level of 0.1–0.3 mm. Tooth preparation (TP) refers to the process of removing part of tooth tissue and preparing specific resistance form, retention form, and finishing line by using tooth-cutting instruments (including rotary cutting tools and non-rotary 1.3.3 The Relationship Between Digital cutting tools) to provide space and supporting structure for Micro Prosthodontics and Minimally future prosthesis. The two core elements of tooth preparation Invasive Dentistry include providing appropriate space volume and corresponding space shape for target restoration. In order to obtain ideal Digital micro prosthodontics is a branch of clinical dentistry restorative space, various guiding techniques are often used based on digital guidance and all or most of diagnosis and for tooth preparation, such as depth-hole-guiding tooth preptreatment operations are carried out under the dental micro- aration technique using silicone rubber guide or TRS guide. scope. But can the use of microscope achieve completely Notably, patients are becoming more anxious and hesiminimal invasiveness? In fact, the main goal of digital micro tate about the irreversible and invasive treatment. Applying prosthodontics is precision, so it is not completely equivalent microscopes into prosthodontics can avoid the adverse facto minimally invasive dentistry. MICD (minimally invasive tors of the traditional restoration with a naked eye and precosmetic dentistry) has a set of dental treatment methods, serve more tooth structure and protect the pulp vitality, using minimally invasive treatment technology to achieve achieving long-term, stable restorative effect. So the final the cosmetic effect. The philosophy of MICD is achieving clinical result will be better than that of naked-eye restoratreatment with least invasiveness and as much as possible tion. By using the microscope, the fixed prosthesis “based preservation of healthy tooth structure based on patients-­ on the endodontic and periodontal health and harmonious oriented and comprehensive considering of the oral function function,” mentioned in this book, can be more easily and esthetic effect. It not only meets the aesthetic require- realized!

Suggested Readings

Suggested Readings 1. Haiyang Y, Junying L.  The concept, clinical design and transfer application of target restoration space. West China J Stomatol. 2015;33(2):111–4. 2. Haiyang Y, Tian L. Application of target restoration space quantity and quantitative relation in precise esthetic prosthodontics. West China J Stomatol. 2016;34(3):223–8.

7 3. Qianqian Z, Xin C, Yuwei Z, et  al. Application of 3D print ing in aesthetic oral rehabilitation. West China J Stomatol. 2018;36(06):656–61. 4. Haiyang Y, Yuwei Z, Junying L, et al. Minimal invasive microscopic tooth preparation based on endodontic, periodontal and functional health. West China J Stomatol. 2019;37(3):229–35.

Part I Analysis, Design and Preclinical Preparation of Micro Prosthodontics

2

Theory and Practice of Target Restorative Space (TRS)

One of the hot professional terms we’ve heard for more than a decade is “restoration-driven implant.” In recent Chinese academic exchanges about implant restoration and orthodontics, we often hear more philosophical expressions such as “starting at the end.” The essence of “restoration” in “restoration-­driven implant” and “end” in “starting at the end” is the subject of this chapter: target restorative space (TRS) and its multiple steps of space transfer. As the three elements and four dimensions theory of color-shape-­ psychology says in my book General Theory of Aesthetic Restoration, color can’t exist alone and must depend on shape to show, while psychology also plays its role through the selection of shape; with the extension of service time of restoration, the three elements of color, shape, and psychology will change with age, and the unharmony of the three elements will be basis of periodic replacement of restoration. Therefore, shape is the most important basis of restorative design, and its essence in terms of operation is TRS. Although the treatment goals of each branch discipline vary, the essential differences are still the methods and means of space transfer which are essentially based on TRS.

2.1

 efinition and Classification of Target D Restorative Space (TRS)

2.1.1 Definition The target restorative space is the minimum reasonable space that the restoration needs to occupy based on the patient’s complaint and current situation as well as ensuring the health of the soft and hard tissues and normal physiological function activities. The clinicians implement analysis and design restoration technologies such as physical or digital restoration design, mock-up and function evaluation, to derive the information about the contour, boundary, arrangement and occlusion relationship of the target restoration by physical measurement or digital technology and obtain the numerical value

requirements in each direction and the relationship between the number of transfers in the subsequent steps. It is “numerical values” rather than vague experience that is relied on as much as possible to accurately guide the entire process of clinical production and restoration fabrication. In the clinical restoration process, the essence of steps of tooth preparation, placing implant and restoration fabrication are transferring the numerical values of the target restorative space between steps. Through the preoperative analysis and design with physical measurement or virtual technology and verifying key parameters of TRS during the operation, the clinicians can accurately and respectively convey information about the boundary and spatial values of the restorative space in the sequential multi-step transfer. On the other hand, the numerical value of unknown key parameters can be easily derived from the mathematical relationship between the TRS and the known quantity value in the sequential multi-step transfer, which will also help the dentist to verify and analyze tooth preparation amount identified in the design phase and precisely provide key parameters of restoration design such as restoration material type and layer thickness to achieve accurate restoration on the target tooth. In implant restorations, it can guide the accurate implanting and help obtain a more ideal implantation site in the missing teeth space, resulting in a better, predictable, and stable effect of restoration-oriented treatment. Therefore, clinical technology relying on numerical requirements combined in digital guide is the cornerstone of digital restoration and implantation.

2.1.2 Classification 2.1.2.1 Classification of Target Restorative Space for Implant For implantation, the target restorative space is the space occupied by the final restoration. The target restorative space can be classified into four types according to the size of the space to be repaired after the soft and hard tissue defects.

© Springer Nature Singapore Pte Ltd. and People’s Medical Publishing House 2022 H. Yu, Digital Guided Micro Prosthodontics, https://doi.org/10.1007/978-981-19-0256-7_2

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2  Theory and Practice of Target Restorative Space (TRS)

1. Ideal Site Target Restorative Space Ideal site target restorative space, referred to as ideal site space (Fig.  2.1) indicates that the target restorative space equals to the natural tooth space. Ideal site space is common in cases of immediate removal and immediate implantation which only need to replicate the original tooth shape. 2. Minimal Site Target Restorative Space Minimum site target restorative space can be simply referred to as minimum site space (Fig. 2.2). It is the minimum space that allows various implants to be placed. This space is common in implant cases where chronic tooth loss has not been repaired. 3. Correct Site Target Restorative Space Correct site target restorative space, referred to as correct site space (Fig. 2.3) is the space expanding between the ideal site space and the minimal site space. This space is common in most cases of implant restoration. 4. Incorrect Site Target Restorative Space Incorrect site target restorative space, referred to as incorrect site space (Fig. 2.4), means that the size of the space for restoration is smaller than the minimum site space or the space is located outside the aforementioned space, which is a contraindication to implanting.

2.1.2.2 Classification of Fixed Restorative Space For fixed restorations, according to the spatial position relationship between TRS and the original tooth, TRS can be classified into internal target restorative space (ITRS), external target restorative space (ETRS), and mixed target restorative space (MTRS) as follows:

1. Internal Target Restorative Space Internal target restorative space, referred to as internal space (Fig. 2.5) means that the TRS is completely inside the unprepared tooth. This kind of space is common in cases where only replication of the original tooth shape is required or in cases where the original tooth shape needs to be reduced. For the same prosthetic design, when TRS is internal target restorative space, the corresponding dental preparation is the largest. The internal space can be classified into the following two types according to whether the target tooth has vital pulp and the relative size between the internal space and the designed amount of tooth preparation (DATP). (a) Class I: The target tooth has vital pulp. (i) Class I sub-category a (class Ia): ITRS = DATP (ii) Class I sub-category b (class Ib): ITRS 6 ≥6

Mesial-distal dimension (mm) (consecutive missing)13 5–7 (anterior teeth)/7–10 (posterior teeth)

Fig. 14.132  The operative region was measured on the cast using the HX Measuring-and-Guiding Kit for Implant

Occlusal dimension for restoration (mm) 5–7 5–7 5–10

266 Table 14.9  Summary of the threedirection dimensions of the operation area on the cast

14  Decisions on Clinical Rehabilitation of Secondary Aesthetic Porcelain Restoration

Site 24 25 Ideal value

Buccal-lingual dimension (mm) 9 10 ≥6

Mesial-distal dimension (mm) (consecutive missing)13 5–7 (anterior teeth)/7–10 (posterior teeth)

Occlusal dimension for restoration (mm) 5–7 5–7 5–10

Fig. 14.133  The operative region was measured on the CBCT model

Table 14.10  Summary of the three-direction dimensions of the operation area on the CBCT model

Site #14 tooth #24 tooth Ideal value

Buccal-lingual dimension (mm) 3.02 6.69 ≥6

Mesial-distal dimension (mm) 6.04 8.33 ≥7 (Bone level)

Bone height (mm) 16.5 13.19 ≥10

14.3 Typical Cases of Secondary Porcelain Aesthetic Repair and Retreatment

Fig. 14.134  Implant position design of #24 and #25

Fig. 14.135  Using an implant indicator to simulate implantation intraorally and on the cast

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14  Decisions on Clinical Rehabilitation of Secondary Aesthetic Porcelain Restoration

Fig. 14.136  Minimally invasive extraction of #24 and #25 residual roots

Fig. 14.137  Creating a hole of one-half depth needed for implant using pilot drill under the guidance of implant indicator

14.3 Typical Cases of Secondary Porcelain Aesthetic Repair and Retreatment

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Fig. 14.138  Checking the orientation of the hole

Place implant

Mesial-distal measurement

Buccal-lingual measurement

Fig. 14.139  Checking after placing implants by using HX Measuring-and-Guiding Kit for Implant

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14  Decisions on Clinical Rehabilitation of Secondary Aesthetic Porcelain Restoration

Fig. 14.140  Error analysis of buccal-lingual orientation of #24 and #25 implants

Fig. 14.141  Error analysis of mesial-distal orientation of #24 and #25 implants

14.3 Typical Cases of Secondary Porcelain Aesthetic Repair and Retreatment

Fig. 14.142  Checking the stability of implants at 6-month follow-up

Fig. 14.143  Analysis of upper restorative space of implant using the double-head T-shape measuring stick

Fig. 14.144  Finishing of dental implant restoration

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Fig. 14.145  Patient filled out the psychological assessment scale after dental implant restoration

14.4 Summary and Prospect The decision tree of secondary aesthetic porcelain restoration provides a reference for the treatment of secondary

restoration cases (Fig. 14.146). TRS guide plays a guiding role in secondary restoration cases. They both lay the foundation for secondary aesthetic porcelain restoration which is based on the health of endodontics, periodontics and functions.

14.4 Summary and Prospect

Fig. 14.146  Clinical decision tree for secondary restoration of porcelain aesthetics

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Suggested Readings 1. Yu HY, Zhao YW, Li JY, et al. Minimal invasive microscopic tooth preparation in esthetic restoration: a specialist consensus. Int J Oral Sci. 2019;11(3):31. 2. Yu HY, Zhao YW, Li JY, et al. Minimal invasive microscopic tooth preparation based on endodontic, periodontal and functional health. West China J Stomatol. 2019;37(3):229–35. 3. Stoll R, Sieweke M, Pieper K, et al. Longevity of cast gold inlays and partial crowns—a retrospective study at a dental school clinic. Clin Oral Investig. 1999;3(2):100–4. 4. Libby G, Arcuri MR, Lavelle WE, et al. Longevity of fixed partial dentures. J Prosthet Dent. 1997;78(2):127–31. 5. Yu HY, Li JY.  The concept, clinical design and transfer application of target restoration space. West China J Stomatol. 2015;33(2):111. 6. Cenci MS, Rosa RPAD, Tatiana PC, et al. Fixed partial dentures in an up to 8-year follow-up. J Appl Oral Sci. 2010;18(4):364–71.

7. Yu HY, Luo T. Application of target restoration space quantity and quantitative relation in precise esthetic prosthodontics. West China J Stomatol. 2016;34(3):223–8. 8. Fradeani M, Redemagni M.  An 11-year clinical evaluation of leucite-reinforced glass-ceramic crowns: a retrospective study. Quintessence Int. 2002;33(7):503. 9. Yu HY, Zhang Q. Application of 3D printing in aesthetic oral rehabilitation. West China J Stomatol. 2018;36(06):656–61. 10. Yu HY. Reconstruction of clinical pathway for esthetic restoration. Chinese J Pract Stomatol. 2015;8(2):65–6. 11. Liu CX, Guo J, Gao J, Yu HY.  Computer-assisted tooth preparation template and pre-designed restoration: a digital workflow. Int J Comput Dent. 2020;23(3):1–12. 12. Gao J, Li J, Liu C, et al. A stereolithographic template for computer-assisted teeth preparation in dental esthetic ceramic veneer treatment. J Esthet Restor Dent. 2020;32(8):763–9. 13. Liu CX, Gao J, Zhao YW.  Precise tooth preparation technique guided by 3D printing guide plate with quantitative hole. West China J Stomatol. 2020;38(3):350–5.

Occlusal Reconstruction Under the Guidance of Target Restorative Space

When clinicians carry out practical clinical operations with the goal of eliminating symptoms, improving function and appearance, it is often difficult to avoid occlusal changes. From the simple occlusal adjustment of a single tooth to the complex occlusal reconstruction of edentulous jaws, the concept of stomatognathic system as a whole cannot be ignored. Since the theory of occlusion was put forward in the middle of the sixteenth century, although different scholars have different understandings about the standard of occlusal contact, it has been universally acknowledged that the goal of dental treatment is to achieve the long-term health and stability of the stomatognathic system including teeth, temporomandibular joint, muscle, and supporting tissue. Therefore, how to take different ways to deal with different occlusal problems and how to make quantitative adjustments according to different occlusal conditions is a thorny problem that dentists often face. This chapter will start with the regular procedure of occlusal reconstruction and analyze typical cases that applied TRS guide technique to occlusal reconstruction from the perspective of clinical practical application.

15.1 Comprehensive Assessment Before Occlusal Reconstruction When facing with some difficult cases involving occlusal problems, clinicians should consider not only the problems of teeth but also the health of the entire oral and maxillofacial system. Through comprehensive functional examination of the oral and maxillofacial system, face-to-face communication between doctors and patients, and detailed collection of basic information of patients, an accurate diagnosis can be obtained, and then a comprehensive and clear treatment plan can be made step by step to lay the foundation for the restoration effect which integrates function and aesthetics in the later stage.

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15.1.1 Clinical Consultation and Risk Assessment Clinical consultation can not only help dentists understand patients’ medical history and dental treatment history but also help them understand patients’ treatment intentions and treatment expectations. At the first visit, it is recommended that the dentist should have a face-to-face conversation with the patient. On the one hand, it can help to establish a good dentist-patient relationship. On the other hand, according to the patient’s response, the dentist can initially judge the health condition of the patient’s oral and maxillofacial system and assess the treatment risk at the same time. According to the chief complaint of the patient, routine psychological evaluation and treatment intention assessment are recommended before operation (Fig. 15.1). If the chief complaint has nothing to do with restorative problems and belongs to psychological factors, dentists are recommended to give up offering dental restorative treatment decisively and suggest patients to receive psychotherapy. If the chief complaint is related to prosthodontic problems and psychological factors are excluded, the next step of clinical examination can be carried out. It should be noted that the follow-up prosthetic treatment is often irreversible. So before treatment, it is necessary to inform the patients of their condition, treatment plan, and the details of possible complications with full respect for patients’ wishes. Only with the informed consent of the patients can the treatment be performed cautiously.

15.1.2 Examination of the Oral and Maxillofacial System The complete examination of the stomatognathic system includes five aspects, that is, dentition examination, periodontal examination, occlusal relation examination, function examination of temporomandibular joint, and masticatory muscle.

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Fig. 15.1  Psychological assessment scale

1. Dentition examination. Check whether the entire dentition is complete, whether any tooth is damaged, whether there is abrasion or attrition of teeth, whether there is dental caries, whether there is fixed prosthetic restoration, whether there is any abnormal reaction during probing and percussion test, and whether radiographic test can be used to evaluate dental pulp treatment and periapical conditions. 2. Periodontal examination. The periodontal attachment level can be obtained by probing the cementoenamel junction and periodontal pocket depth. For deep periodontal pocket at individual sites, the occlusal cause can be excluded after probing test and subsequent bite test which can detect dental calculus, gingival bleeding, root bifurcation lesions, etc. A periodontal chart can reflect the basic periodontal conditions in the patient’s mouth. The symmetry and aesthetics of the attached gingiva in the aesthetic area can provide important information for the later aesthetic design of restoration, and the width of the attached gingiva in the missing tooth area can also provide important evidence for the choice of treatment. When it comes to the examination of intraoral restoration, it is necessary to check whether the edge of the restoration violates the biological width. When the biological width involved in occlusal reconstruction is invaded, if necessary, crown lengthening or orthodontic traction

should be considered to help reconstruct periodontal tissue in accordance with physiological health. 3. Examination of occlusal relation. When the mandibular is on the intercuspal position, the occlusal force of the whole dentition is evenly distributed, and by examining the occlusal force with occlusal paper, it is found that most of the occlusal points of the whole dentition are in the posterior area and the number and distribution of the occlusal contact points on the left and right sides are close to each other. During the protrusive movement, the occlusal contact points are at the marginal ridges or incisal edge of anterior teeth, and there are no interference points in posterior teeth. In the lateral movement, the occlusal contact points are mainly on canines (for group function occlusion, the occlusal contact points are in canines and premolars at the same time), and there was no occlusal interference point in posterior teeth. If any clear premature contact or interference point is found by the occlusion test, adjust it immediately to see whether the accompanying occlusion symptoms are relieved. If the occlusion problems cannot be clearly defined, it is suggested to have some auxiliary tests before handling them. 4. Temporomandibular joint examination: check whether there is popping, pain, and dyskinesia of the temporomandibular joint. Exam the jaw popping by palpation test. If any, record the location and properties of the pop-

15.2  Typical Cases of Occlusion Reconstruction Aided by the TRS Guide

ping. If the joint area has symptom of pain, palpate the joint area and the muscle ligaments in sequence. Care should be taken to distinguish the arthralgia pain and masticatory muscle pain. The functional examination of the TMJ includes examination of the mandibular movement when opening the mouth and the width of mouth opening. Ask the patient to slowly open his/her mouth to the maximum, and observe the movement of the mandible. If there is deflection or restriction when the patient opens the mouth, try to record the type of the abnormal mandibular movement. The examination of mouth opening width includes the width of free mouth opening and passive mouth opening and the range of protrusive movement and lateral movement range. Generally speaking, the width of free mouth opening is 37–45 mm, and the range of lateral movement is 9–12 mm. 5. Masticatory muscle examination. Healthy masticatory muscles should not present palpation pain when they are functioning. Palpation discomfort indicates hyperfunction or disharmony of muscles. When carrying out palpation test, exam from extra-orally to intra-orally the temporal muscle, masseter muscle, medial pterygoid muscle, digastric muscle, sternocleidomastoid muscle, and lateral pterygoid muscle in turn. When positive signs are found which indicate that the masticatory muscle has dysfunction, hasty prosthetic treatment will affect the occlusion of the definitive restoration because the position of the condyle is unstable now. It is recommended not to act rashly before the muscle returns to health. 6. Aesthetic evaluation. The prosthetic treatment plan involving occlusal problems should take into account both functional health and beautiful appearance. When using digital photos and research models to record the initial aesthetic information of patients and the DLD/ DSD technology to do aesthetic evaluation before treatment, dentists should focus on not only the aesthetic effect of a single tooth but also the coordination of teeth in aesthetic area with the surrounding lip and facial tissue. Aesthetic evaluation is the premise of function and aesthetic design. The incisal edge position, tooth proportion, and arrangement of the anterior tooth area are of great significance for the coordination of the whole stomatognathic system.

15.1.3 Radiographic Examination Radiographic examination can provide the information which is invisible for naked eyes and the important diagnostic evidence for the integrity of stomatognathic system. For different

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diagnostic needs, choose different radiographic examinations which commonly include periapical or panoramic X-ray, cone beam computed tomography (CBCT), magnetic resonance imaging (MRI), and so on. Periapical X-ray is mainly providing information about the morphology of the teeth, pulp cavity, and periodontal tissue of a single tooth and is used to determine the diagnosis of specific tooth. Panoramic X-ray, providing information about the whole mouth, jaw, maxillary sinus, and temporomandibular joint, has wider examination range than periapical X-ray, but it is generally used merely as reference because of problems of image overlap and distortion. CBCT, displaying the information of all the teeth and bony structures such as jaw, maxillary sinus, and temporomandibular joint in multiple sections, avoids the image distortion, a common problem that occurred to panoramic X-ray, and consequently is widely used. MRI is generally used for imaging of soft tissues. For patients who need radiographic examination of soft tissues like temporomandibular joint disc, muscle, and ligament, MRI can offer better results than other methods. Note that MRI for temporomandibular joint disc cannot be replaced by panoramic X-ray or CBCT.

15.1.4 Mounting of Diagnosis Casts onto the Articulator The upper and lower jaw casts are obtained by taking the impression. Transfer the maxillary cast to the articulator through the face bow. After the centric relation was recorded intro-orally, the mandibular model is transferred to the articulator extra-orally. With the diagnosis casts mounting on the articulator, the sequence teeth contact and the occlusal relation of the dentition in static and dynamic state can be observed in all directions extra-orally, which provides an accurate record of the jaw position for the quantitative analysis of TRS guide technique.

15.2 Typical Cases of Occlusion Reconstruction Aided by the TRS Guide The advantages of target restorative space (TRS) technology in real-time measurement and precise preparation guidance just make up for the blank of quantitative spatial analysis and design transfer of occlusal reconstruction. This section introduces and analyzes the application of TRS in typical cases of occlusal reconstruction, reviews the basic process of occlusal reconstruction, and focuses on the clinical application of TRS guide technique.

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15.2.1 A Case of Secondary Aesthetic and Functional Porcelain Restoration of Maxillae and Mandible Aided by TRS Guide Male, 65 years old. Chief complaint: Unsatisfaction with the appearance of full mouth restoration and facial muscle pain after dental restoration for 3 months. Current medical history: Patient had full mouth crown and bridge restoration half a year ago and was not satisfied with the aesthetic effect; 3 months ago he felt facial muscle pain during mastication; 2 months ago he received root canal treatment of lower anterior tooth, which, however, did not solve the problem of pain. So now patient asked for treatment (Fig. 15.2). Past medical history: Patient denied the treatment history of periodontics and other dental specialties and also denied systemic diseases of cardiovascular disease, diabetes, etc., as well as allergy. General condition and family history: No special circumstance. Based on the decision tree for secondary aesthetic porcelain restoration, we would perform psychological evaluation, previous treatment evaluation, and target restorative space evaluation and formulate a treatment plan for secondary restoration. 1. Psychological evaluation. According to the patient’s complaint “being unsatisfied with the appearance of full mouth restoration, and facial muscle pain after dental restoration for 3 months,” a psychological evaluation must be performed for the patient before surgery. The patient had little satisfaction with his own teeth which had a great impact on his social life but little effect on his emotions. He had a high degree of anxiety about the appearance of the teeth and 5-point aesthetic expectation for restoration. This was a patient in the need of conventional aesthetics.

Fig. 15.2  Porcelain crowns for upper anterior teeth, temporary restorations for lower teeth

According to the psychological evaluation, it was found that the main complaint of the patient was related to the restoration problem, and the possibility was ruled out that the patient came to a doctor because of adverse psychological factors. Next we would evaluate the rationality of the previous restoration plan (Fig. 15.3). 2. Previous treatment evaluation (a) The patient’s maxillofacial symmetry was examined extra-orally, and no significant abnormalities were found in the lower 1/3 of the face (Fig. 15.4). (b) Palpation of mastication and TMJ area muscle revealed tenderness in the masseter and temporal muscles on the left and right sides of the patient (Fig. 15.5). (c) The examination of mandibular movement found no abnormal sound such as joint popping or grazing sound, no restriction or aberrant types of the movement, and the mouth opening width was normal (Fig. 15.6). (d) Dentition examination showed #16 tooth, #14 tooth, #12 tooth, #22 tooth, #36 tooth, #37 tooth, #47 tooth missing, #17–23 all ceramic bridge restoration, #24– 27 temporary crown restoration, and #35–46 temporary crown restoration; all the intraoral teeth had been treated with root canal therapy, and the remaining teeth had no percussion pain, no obvious loosening, cold and heat sensitivity, or other symptoms (Fig. 15.7). (e) Performed the periodontal examination and filled in the periodontal chart. It was found that the gingiva of many teeth in the mouth was reddish and swollen, and there was bleeding on probing and attachment loss of many teeth (Fig. 15.8). (f) Examination of the occlusal relation revealed the loss of the original occlusal relation. No obvious premature contact, occlusal interference, and other occlusion problems were found in the mouth (Fig. 15.9). (g) Radiographic examination: No tooth in the mouth was found obvious low-density shadow around the apex in the periapical X-ray, and CT showed no obvious abnormality of the bone in the TMJ area (Fig. 15.10). (h) Based on the above evaluation, the following diagnoses were obtained: dentition defect (#12 tooth, #14 tooth, #36 tooth, #37 tooth, #47 tooth), tooth defects (#11 tooth, #13 tooth, #15 tooth, #17 tooth, #21 tooth, #23 tooth, #24–27 teeth, #35–46 teeth), bilateral masticatory muscle dysfunction, and severe chronic periodontitis (Fig. 15.11). According to the diagnosis, the dentist made the corresponding treatment plan. The patient first needed to eliminate periodontitis through sequential periodontal comprehensive treatment. At the same time, the

15.2  Typical Cases of Occlusion Reconstruction Aided by the TRS Guide

Fig. 15.3  The psychological evaluation showed this was a patient in need of conventional aesthetics

Fig. 15.4  Extra-oral examination

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Fig. 15.5  Examination of mastication muscles and temporomandibular joint ligament revealed mastication tenderness Fig. 15.6  Examination of TMJ area

masticatory muscle dysfunction was treated by TMJ specialists to obtain a stable occlusal r­elationship. After completing these two steps of treatment, restorative plan was determined about the restoration shape, color, etc. With the informed consent of the patient, we were going to remove the old restorations and restore #14 tooth, #24 tooth with implants, and #21 tooth and #22 tooth with crowns.

3. Removal of the old restorations, determination, and implementation of the final treatment plan (a) Periodontal treatment: According to the periodontal sequence treatment process, basic periodontal treatment and oral hygiene education were performed (Fig. 15.12). Three months later, a detailed clinical examination was performed to the patient to fill in a periodontal

15.2  Typical Cases of Occlusion Reconstruction Aided by the TRS Guide

chart again. It was found that the periodontal inflammation disappeared, indicating that the patient could move on to the next step of the treatment process (Fig. 15.13). (b) Obtain a stable occlusion to solve functional problems: Transfer the occlusal relation of the occlusal splint through the articulator to make the first pair of transitional dentures (Fig. 15.14). Put the transitional dentures into the patient’s mouth (Fig. 15.15). After the patient wore the first transitional denture for 3 months, followed him up. No tenderness of masticatory muscle and temporomandibular joint ligament were found by palpation, no obvious abnormality was found by radiographic examination, and the occlusal relation of the patient was stable (Fig. 15.16). After the periodontitis subsided and oral hygiene maintained well, and the masticatory muscle tenderness disappeared and the occlusal relationship was stable, the secondary

Fig. 15.7  Dentition examination

Fig. 15.8  Periodontal chart

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repair could be done for the defected dentition and defected teeth. Considering the previous restorations of all-ceramic bridge for detention defect, we planned to keep the all-­ ceramic bridge design in the upper anterior tooth area and chose the implant restorations in the posterior tooth area due to the patient’s strong occlusal force and difficulty in cleaning. As for the restoration plan for tooth defects, the lower anterior teeth were designed to be restored by full crown supported by fiber post because of inadequate remaining tooth structure; other defected teeth were designed to be repaired with full crowns (Fig. 15.17). The DLD virtual aesthetic analysis was performed on the intra-oral photograph of the frontal view. The results showed that the patient had a median laugh line and the width of the upper anterior teeth was coordinated, but the width and height of the central incisors were larger (Fig. 15.18) and the free gingival margin curve looked inharmonious. The old restorations had unnatural color and looked dull. Using a dynamic facial scanner, the dynamic facial scan model of the patient was obtained, and further pronunciation analysis was performed on the model (Fig. 15.19). The analysis results of pronouncing “M,” “E,” “F,” and “V” suggested that if the incisor edge of #11 tooth and #21 tooth remained unchanged or was increased by 0.5 mm, the axial direction of the teeth won’t change. Based on DLD virtual aesthetic analysis and pronunciation analysis, the virtual aesthetic design was completed on intra-oral picture of the frontal view (Fig. 15.20). Considering that the patient had an inharmonious gingival margin curve, a median laugh line and the clinical crown-root ratio of less than 1:2 which resulted in high risk of crown lengthening surgery, we chose to keep the existing position of the gingival margin curve unchanged after communicating with dental technician.

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Fig. 15.9  Occlusal examination

Fig. 15.10  Radiographic examination

15  Occlusal Reconstruction Under the Guidance of Target Restorative Space

15.2  Typical Cases of Occlusion Reconstruction Aided by the TRS Guide Fig. 15.11  Diagnosis of the patient

Fig. 15.12  Perform the periodontal sequence treatment

Fig. 15.13  Periodontal chart of the patient 3 months later

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Fig. 15.14  Transfer the occlusal relation of the occlusal splint

Based on the DLD virtual aesthetic analysis and design, a solid diagnostic wax-up was made (Fig. 15.21). Use the diagnostic wax-up approved by the dentist, patient, and technician to make a TRS guide. First step was to obtain the digital diagnostic wax-up by scanning the solid model; then we designed the TRS guide in the EXOCAD software. After importing the data of the digital design into the 3D printer, we got a 3D printing TRS guide (Fig. 15.22). The inner surface of the guide corresponded to the outer surface of the diagnostic wax-up. The guide was placed into in the mouth. After confirming the guide is fully seated, the existing space was measured, which was to measure the distance from the tooth surface to the outer surface of the guide through the premade holes and subtracted it by the thickness of the guide to obtain the depth of the existing space (Fig. 15.23). We evaluated the existing space of the patient’s remaining teeth. According to the material selection decision tree, as the color of the patient’s abutment teeth was normal and the thickness of the porcelain layer required for restoration was less than 1  mm, the monolithic high-translucent zirconia

material was selected to meet the strength requirements in the limited repair space. According to the designed thickness of the monolithic high-translucent zirconia material and the existing depth, the preparation plan was determined that only three teeth need to be prepared. The space analysis of the target restorative space and the preparation plan are shown in the figure below (Fig. 15.24). Guided by the TRS guide, depth holes were made with a depth cutting bur. These holes then guided the completion of tooth preparation (Fig. 15.25). During tooth preparation, the occlusal relation of the first pair of transitional dentures was transferred to the articulator. A second pair of transitional dentures was made and put into the patient’s mouth to further stabilize the occlusal relation of the patient (Fig. 15.26). The design of the implant guide was completed under the guidance of TRS guide. With the help of the guide, implants were placed into the bone successfully. Four months later when the implants had stable osseointegration and the ISQ value reached 80, implant-supported transitional dentures

15.2  Typical Cases of Occlusion Reconstruction Aided by the TRS Guide

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Fig. 15.15  Transitional denture in patient’s mouth

were worn to further ensure the stability of the patient’s occlusal relation (Fig. 15.27). We assessed the function and occlusion of the transitional denture. After confirming that the function and occlusion were stable and that the patient was satisfied with the appearance of the transitional denture, we replicated its appearance to make the definitive restoration (Figs. 15.28 and 15.29). The patient was followed up 1 year after the definitive restoration was given to him. The occlusal examination showed a stable occlusal relation without obvious premature contact or occlusal interference points. And periodontal condition was healthy (Figs. 15.30 and 15.31). At 2-year follow-up, we found the restoration having margin of good fitness (Fig. 15.32). The patient was asked to fill in the psychological assessment scale again. It was showed that he was very satisfied with the restoration and less anxious about the tooth appearance, and teeth had little impact on his social life and mood. The patient scored 9 points for the restorative aesthetics which was higher than the aesthetic expectation value before treatment (Fig. 15.33).

15.2.2 A Case of Secondary Aesthetic Porcelain Restoration of Maxillae and Mandible Aided by TRS Guide Male, 82 years old. Chief complaint: Porcelain crown cracking for 3  years after restoration. Current medical history: Patient received #13, #14, #16, #25, #26 implants 5  years ago, and restoration of #14–16 fixed bridge supported by implants, #25 and #26 joint crowns supported by implants, #31–34 porcelain bridge and #41–44 porcelain bridge, #35 and #36 joint crowns supported by implants, and #45 and #46 joint crowns supported by implants. Patient was unsatisfied with the appearance and function of the restoration, so he came for a treatment (Fig. 15.34). Past medical history: Patient admitted having received oral surgery and prosthetic treatment and denied allergies to metal and dental materials. He also denied coronary heart disease, diabetes, infectious diseases such as viral hepatitis

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Fig. 15.16  The muscle palpation and radiographic examination in the 3-month-later follow-up showed that functional problems had been solved

and tuberculosis, smoking history, sleep bruxism, mouth breathing, and medical allergies. General condition and family history: No special circumstance. Based on the decision tree for secondary aesthetic porcelain restoration, we would perform psychological evaluation, previous treatment evaluation, and target restorative space

evaluation and formulate a treatment plan for secondary restoration. 1. Psychological evaluation: According to the patient’s complaint that “porcelain crown cracking for 3 years after restoration,” psychological evaluation must be performed before operation. The psychological evaluation scale

15.2  Typical Cases of Occlusion Reconstruction Aided by the TRS Guide

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Fig. 15.17  Treatment plan for secondary restoration Fig. 15.18  DLD virtual aesthetic analysis on the intro-oral photograph of the front view

Fig. 15.19  Pronunciation analysis

filled by the patient showed that he was not satisfied with his teeth which had some negative influence on his social life and mood, and he was anxious about the appearance of the teeth severely. He had aesthetic expectation of 5

points and was a patient with the need of conventional aesthetics. The chief complaint problem was related to restorations, and psychological factors were excluded. So we could then evaluate the previous treatment (Fig. 15.35).

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Fig. 15.20  DLD virtual aesthetic design

Fig.15.21  A solid diagnostic wax-up was made on the basis of virtual aesthetic design

Fig. 15.22  3D printing TRS guide

Fig. 15.23  Depth of existing space = distance from the tooth surface to the outer surface of the TRS guide—TRS guide thickness

15.2  Typical Cases of Occlusion Reconstruction Aided by the TRS Guide

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Fig. 15.24  The determined preparation plan

Fig. 15.25  Tooth preparation under the guidance of depth holes

2. Previous treatment evaluation (a) Extra-oral examination showed that the patient had symmetry head and face without obviously abnormal portion, undamaged maxillofacial skin, and low laughter line. No muscle tenderness and other abnormalities were found by palpation in masticatory muscle and TMJ area. When opening the mouth, there was no joint popping or grazing sound, and the

­ andibular movement had no restriction or aberrant m pathway. The mouth opening width was normal (Fig. 15.36). (b) Dentition examination: #14–16 teeth were restored with implants and fixed bridge. #25 tooth and #26 tooth were restored with implants and joint crowns which had porcelain cracking but no loosening. The implant abutment of #13 tooth was exposed and

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Fig. 15.26  Have the patient to wear the second pair of transitional dentures to stabilize the occlusal relation

Fig. 15.27  Implantation and follow-up restoration procedure

Fig. 15.28  Intra-oral view after final restoration

Fig. 15.29  Extra-oral view after final restoration

15.2  Typical Cases of Occlusion Reconstruction Aided by the TRS Guide

Fig. 15.30  Intra-oral frontal view at 1-year follow-up

Fig. 15.31  Periodontal chart at 1-year follow-up

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inclined to the buccal side with its edge about 10 mm away from the occlusal plane of the posterior teeth. #31–34 teeth, #41–44 teeth were restored with joint PFM crowns that had poor margin fitness. #35 tooth, #36 tooth, #45 tooth, and #46 tooth were restored with implants and joint crowns without loosening. There was crossbite in anterior region and no overjet or overlap in posterior region. Soft tissue was found no obvious abnormality (Fig. 15.37). (c) After performing meticulous periodontal examination and filling in the periodontal chart, it was found that there were many reddish and swollen gums in

the patient’s mouth, bleeding on probing, and attachment loss of multiple teeth (Fig. 15.38). (d) Radiographic examination: There were multiple implants in the patient’s mouth. Low-density shadows were seen around the apex of #32 tooth to #42 tooth and the other teeth were found no obvious low-­ density shadow around the apex (Fig. 15.39). (e) According to the results of the previous treatment evaluation, the following diagnosis was obtained: maxillary dentition missing, mandibular dentition defect (#35–37 teeth, #45–47 teeth), tooth defects (#31–34 teeth, #41– 44 teeth), and chronic periodontitis (Fig. 15.40).

Fig. 15.32  Detailed view at 2-year follow-up

Fig. 15.34  Intra-oral view at first visit

Fig. 15.33  The patient filled in the psychological assessment scale at 2-year follow-up

15.2  Typical Cases of Occlusion Reconstruction Aided by the TRS Guide

Fig. 15.35  The psychological evaluation excluded the negative psychological factors

Fig. 15.36  Extra-oral examination

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Fig. 15.37  Dentition examination

Fig. 15.38  Periodontal chart

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15.2  Typical Cases of Occlusion Reconstruction Aided by the TRS Guide

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Fig. 15.39  Radiographic examination

Fig. 15.40  Diagnosis of the patient

3. Removal of the old restorations, determination, and implementation of the final treatment plan We analyzed problems according to the diagnosis. In periodontal aspect, there were multiple plaque accumulation and bleeding on probing; in occlusal aspect, there were crossbite in anterior region and no overbite or overlap in posterior region. When it comes to aesthetics, #14– 16 restoration of implants and fixed bridge and #25–26 restoration of implants and joint crowns had poor aesthetic appearance and margin fitness. #31–34, #41–44 restorations of joint PFM crowns also had poor appearance and margin fitness (Fig. 15.41).



Based on the analysis and summary of the patient’s problems, we selected the most appropriate treatment for each step and formulated the final treatment plan (Fig. 15.42). Following the plan, the restoration treatment was carried out step by step. Firstly, the restorative material was selected taking both strength and aesthetics into account. After the dentist-patient-technician communication, double-­layer porcelain structure was determined of zirconia inner crown and porcelain veneering for anterior region, and single-layer porcelain structure of monolithic high-translucent zirconia crown was determined for posterior region (Fig. 15.43). (a) According to the treatment plan, we took measures to control acute symptoms (Fig. 15.44). The first step in the acute symptom control phase was to remove the old restorations of the mandibular anterior teeth and to complete the root canal treatment of the lower anterior teeth (Fig. 15.45). The second step of the acute symptom control phase was to carry out basic periodontal treatment and oral health education. Three months after basic periodontal treatment, the patient’s periodontitis was found having subsided. Now we could go on to the phase of disease control. (b) Disease control phase (Fig. 15.46).

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Fig. 15.41  Summary and analysis of the patient’s existing problems

Fig. 15.42  Treatment plan of the patient

15.2  Typical Cases of Occlusion Reconstruction Aided by the TRS Guide

297

Fig. 15.43  Selection of restorative materials choice

Fig. 15.44  Acute symptom control phase

The first step of disease control phase was to do the implanting design and implant guide design under the guidance of TRS (Fig. 15.47). Second, we finished the implant surgery following the implanting plan (Fig. 15.48). After implant surgery, radiographic examination was performed to check the position of the implant. All the implants were located in the ideal implant site (Fig. 15.49). Nine months after the implantation, the patient was followed up and found having good osseointegration around the implants with the ISQ of 80. The soft tissue at the implant site was reshaped (Fig. 15.50). The third step of the disease control phase was to complete the maxillary restoration and form a stable occlusal relation.

Firstly, we made a custom tray and used it to make impressions (Fig. 15.51). Then we fabricated the plaster cast and made the first diagnostic wax-up on it (Fig. 15.52). Try-in of the first diagnostic wax-up was carried out. Then we checked and make sure that the vertical distance was appropriate and occlusal relation was stable (Fig. 15.53). After confirming that the vertical distance was appropriate and the occlusal relation was correct, we transferred the occlusal relation to articulator (Fig. 15.54). Then we fabricated the second diagnosis wax-up and tried it in the patient’s mouth (Fig. 15.55). We scanned the cast and wax-up to obtain the corresponding digital data and designed the framework in EXOCAD software. Then the framework was fabricated (Fig. 15.56). We tried the framework in the mouth and checked the fitness of the framework (Fig. 15.57). Then we sent the digital data to the dental technician to further manufacture the high-translucent zirconia inner crowns on the framework (Fig. 15.58). On the high-translucent zirconia inner crown, layered stacking was carried out under a microscope (Fig. 15.59). The final restorations were finally completed (Fig. 15.60). We tried the final maxillary restoration in the patient’s mouth to make sure that the occlusal relation was stable and the restoration margin fitted well (Fig. 15.61).

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Fig. 15.45  X-rays of mandibular anterior teeth after root canal treatment

Fig. 15.46  Disease control phase



The crowns were adhered(Fig. 15.62), and the artificial gingiva was made to meet the requirements of pink aesthetics (Fig. 15.63). The final maxillary restoration was completed (Fig. 15.64). The final maxillary dental prosthesis was placed in the mouth, having good margin fitness, appearance, and color (Figs. 15.65 and 15.66). (c) Function recovery phase (Fig. 15.67). The first step in the function recovery phase was to transfer the occlusal relation again (Fig. 15.68).

According to the virtual DSD/DLD aesthetic analysis, the wax-up was designed and made. Aesthetic preview was performed in the mouth, and the patient was satisfied with the aesthetic appearance (Fig. 15.69). Using a diagnostic wax-up approved by the dentist, patient, and technician, a transparent TRS guide was made by compressing the dental membrane (Fig. 15.70). Before tooth preparation, shade selection was done using Vita 3D Master shade guide, and the result was 2 M2 (Fig. 15.71). The measurement of restorative space was done monitored by the TRS guide, which was to measure the distance from the tooth surface to the outer surface of the guide through the premade opening holes and subtracted it by the thickness of the guide to obtain the depth of the existing space (Fig. 15.72). According to the target thickness required by the monolithic high-translucent zirconia material and the measured existing depth, the preparation scheme was determined. It was found that the existing depth of all the teeth met the minimum thickness of 0.6  mm required by the high-translucent zirconia material, so no more preparation was required, and all we needed to do was refining the margin (Fig. 15.73). After the final restorations were finished, we tried them in the mouth, and the patient was satisfied with the final aesthetic appearance (Fig. 15.74).

15.2  Typical Cases of Occlusion Reconstruction Aided by the TRS Guide

Fig. 15.47  Make the implanting plan under the guidance of TRS

Fig. 15.48  Implant surgery

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Fig. 15.49  Radiographic examination after implant surgery

Fig. 15.50  9 months after implant surgery, soft tissue was reshaped

After confirming the fitness, adjacency, and occlusion of the prosthesis, we cemented the mandible prosthesis and cleared the excessive adhesive. The restoration was finally completed (Figs.  15.75 and 15.76). Comparing intro-oral views before and after the secondary restoration, it could be seen that the restoration significantly improved the aesthetic effect of the anterior teeth (Fig. 15.77). One year later, the patient came back with the definitive prosthesis (Fig. 15.78). The psychological evaluation showed that he was satisfied with the prosthesis with little anxiety about the appearance of teeth and the teeth had little impact on his social life and mood. He scored 8 points for the aesthetic effect (Fig. 15.79).

15.2.3 A Case of Occlusal Reconstruction Restored by Implant-Supported Fixed Prosthesis with the Aid of Whole-­ Process Digital Guidance Male, 45 years old. Chief complaint: Most teeth were missing in the mouth, with the remaining teeth loose for several years. Current medical history: The patient suffered from loose upper left, upper right, and lower right posterior teeth several years ago and underwent extraction of upper left, upper right, and lower right posterior teeth and did not recover the chewing function of both posterior teeth. The remaining teeth in the mouth were loose, and the chewing function was limited. Now he came for a treatment (Fig. 15.80).

15.2  Typical Cases of Occlusion Reconstruction Aided by the TRS Guide

Fig. 15.51  Make impression using a custom tray

Fig. 15.52  The first diagnosis wax-up

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Fig. 15.53  Try-in of the first diagnosis wax-up

Past medical history: Patient denied the history of periodontal treatment; denied the history of cardiovascular disease, diabetes, and other system diseases; and denied the history of allergy. He had a smoking history of more than 15 cigarettes per day for over 20 years. Based on the decision tree for secondary aesthetic porcelain restoration, we would perform psychological evaluation, previous treatment evaluation, and target restorative space evaluation and formulate a treatment plan for occlusal reconstruction. 1. Psychological evaluation: According to the patient’s complaint “most teeth were missing with the remaining teeth loose for several years,” psychological evaluation must be performed before operation. The psychological assessment scale filled by the patient showed that he was not satisfied with his teeth which had some negative influence on his social life and mood, and he was anxious about the appearance of the teeth severely. He had aesthetic expectation of 5 points and was a patient with the

need of conventional aesthetics. The chief complaint problem was related to restorations, and psychological factors were excluded. So we could then evaluate the previous treatment (Fig. 15.81). 2. Previous treatment evaluation (a) Extra-oral examination showed that the patient had symmetry head and face without obviously abnormal portion, undamaged maxillofacial skin, and low laugh line (Fig.  15.82). No muscle tenderness or other abnormalities were found by palpation in masticatory muscle and TMJ area. When opening mouth, there was no joint popping or grazing sound, and the mandibular movement had no restriction or aberrant pathway. The mouth opening width was normal (Fig. 15.83). (b) Dentition examination: #14–17 teeth,#24–27 teeth, #36 tooth, #32 tooth, #41–42 teeth, #45 tooth, and #46 tooth were missing and inclined to the missing gap. #38 was elongated, and the opposite tooth was missing. #12, #31, and #34 were III° loosened, and

15.2  Typical Cases of Occlusion Reconstruction Aided by the TRS Guide

Fig. 15.54  Transfer the occlusal relation

Fig. 15.55  Fabrication and try-in of the second diagnosis wax-up

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Fig. 15.56  Design and fabrication of the framework

Fig. 15.57  Try-in of the framework

Fig. 15.58  High-translucent zirconia inner crowns

15  Occlusal Reconstruction Under the Guidance of Target Restorative Space

15.2  Typical Cases of Occlusion Reconstruction Aided by the TRS Guide

Fig. 15.59  Layered stacking

Fig. 15.60  Crown restorations

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#13 tooth, #11 tooth, #21–23 teeth, #37 tooth, #35 tooth, #33 tooth, #43 tooth, #44 tooth, and #47 tooth were II° loosened, and #38 tooth was I° loosened. Maxillary anterior teeth area was tilt to labial side. Anterior teeth had I° overjet and II° overlap. There is no occlusion in the posterior area and no obvious abnormalities in soft tissue (Fig. 15.84). (c) Periodontal examination: After performing meticulous periodontal examination and filling in the periodontal chart, it was found that most teeth had BOP(+). The gingiva of all the remaining teeth receded to the upper 1/3 to the middle 1/3 of the root;

Fig. 15.61  Try-in of the final maxillary restoration

Fig. 15.62  Cement crowns

the average periodontal attachment loss of all the teeth in the mouth was 7.2 mm (Fig. 15.85). (d) Radiographic examination: The periapical alveolar bone of the #23 tooth was absorbed to the middle 1/3 of the root; #13–22 teeth, #37 tooth, #38 tooth, #33 tooth, #31 tooth, #43 tooth, #44 tooth, and #47 tooth were absorbed to the apical 1/3. No obvious low-­ density shadows were around the apex. Alveolar bone of upper and lower jaw is acceptable (Fig. 15.86). (e) According to the results of the evaluation, the following diagnosis was obtained: maxillary and mandibular dentition defect (#14–17 teeth, #24–27teeth, #36 tooth, #32 tooth, #41–42 teeth, #45 tooth, #46 tooth), #38 tooth prolonged, chronic periodontitis (severe) (Fig. 15.87). 3. Determination and implementation of the final treatment plan According to the diagnosis, we analyzed problems and formulated a corresponding treatment plan. The patient had no contact in bilateral posterior region, and the anterior teeth were loose and lacked a stable occlusal relationship. The remaining teeth in the mouth were loose and tilt obviously. Combined with the CBCT examination results, #13–23 teeth, #37 tooth, #38 tooth, #35 tooth, #33 tooth, #31 tooth, #43 tooth, #44 tooth, and #47 tooth had no value for preservation. It was recommended to extract the remaining teeth, and the remaining teeth were planned to be removed immediately, implanted immediately, and restored immediately (“three immediately treatment plan”). According to the patient’s bone mass, the type, and material of the definitive restoration, three plans were provided for the patient to choose from, that is, complete denture, implant-supported overdenture, and implant-­ supported fixed prosthesis (Fig.  15.88). We discussed with the patient about all three plans in detail, including the treatment process, cost, period, and possible compli-

15.2  Typical Cases of Occlusion Reconstruction Aided by the TRS Guide

Fig. 15.63  Make artificial gingiva

Fig. 15.64  The maxillary restoration

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Fig. 15.65  Intraoral view of the maxillary restoration

Fig. 15.66  Facial picture of the patient with the maxillary restoration

15.2  Typical Cases of Occlusion Reconstruction Aided by the TRS Guide

cations. Combined with the patient’s subjective wishes and economic conditions, we finally decided on the implant-supported fixed prosthesis restoration plan. After obtaining the patient’s informed consent, the implant restoration plan was implemented. Based on the analysis and summary of the patient’s problems, we selected the most appropriate treatment for each step and formulated the final treatment plan (Fig. 15.89). Determination of the vertical dimension of occlusion and the occlusal relationship: we exported the preoperative CBCT data to STL format to construct a three-dimensional image of the upper and lower jaws (Fig. 15.90) and designed a personalized Gothic bow in the software Meshmixer. The base of the 3D printing custom Gothic bow took used of the gap between the remaining teeth to assist in positioning in the mouth. The negative appliance on the working surface of the base was

Fig. 15.67  Function recovery phase

Fig. 15.68  Transfer the occlusal relation

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designed to lock to the metal plate of the Gothic bow. The 3D printing resin models of the maxillary and maxillary dentitions based on the oral scan data before surgery were used to test the retention and stability of the custom Gothic bow to ensure a good position in the mouth (Fig. 15.91). We set the custom Gothic bow in the mouth, adjusted the adjustment screw of the metal plate of the Gothic bow, and locked the adjustment screw after the height of the lower 1/3 face was appropriate to determine the vertical dimension of occlusion (Fig.  15.92). Then we put red wax on the metal plate of the upper Gothic arch and instructed the patient to move forward and laterally. The arrow tip of the metal plate of the maxillary Gothic bow pointed to the position corresponding to the central relation or adaptive centric relation. After this position was determined, occlusal silicone rubber was injected between the upper and lower jaws to fix them in the centric relation. And the patient was instructed to take CBCT with wearing the custom Gothic bow (including bilateral temporomandibular joints and external auditory canal) and received a facial scan (Fig. 15.93). We used the newly taken CBCT data to reconstruct the three-dimensional image of the upper and lower jaws in the software Blue Sky and imported it to Meshmixer. Then we set the marking points of arbitrary hinge-axis based on the Bergstrom points which were located 10 mm in front of the Porion point and 7  mm below the Frankfort plane. This parameter settings of virtual articulator was finished by matching the arbitrary hinge-axis position with the facial scanning data. After that, 3D images of the facial scanning, intraoral scanning, and skull reconstruction were superimposed within the dental CAD software to create a virtual patient. The implant site design, osteotomy design, and temporary restoration design can be performed on the virtual patient (Fig. 15.94).

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Fig. 15.69  Aesthetic mock up

Fig. 15.70  Transparent TRS guide

Fig. 15.71  Shade selection

We determined the target restoration space based on the temporary restoration design of the virtual patient (Fig. 15.95) and completed the osteotomy design and implant site design with the aid of the target restoration space (Fig. 15.96). In order to improve the accuracy of the temporary restoration, a three-in-one stackable guide, that is, a combination of osteotomy guide, implant surgical guide, and immediate restoration, was designed to match the clinical implementation

steps. The anchoring structure realized the connection and retention between the three guides (Figs. 15.97 and 15.98). Before the surgery, the digital stackable guide was placed on the 3D printing resin models of maxillary and mandibular jaws to ensure accurate matching and good stability (Fig. 15.99). According to the implant surgery plan, we extracted the loose teeth firstly (Fig. 15.100).

15.2  Typical Cases of Occlusion Reconstruction Aided by the TRS Guide

Fig. 15.72  Tooth preparation monitored by transparent TRS guide

Fig. 15.73  No more tooth preparation was needed except refining the margin

Fig. 15.74  Try-in of the definitive mandibular restorations

Fig. 15.75  Frontal view of the mandibular restorations

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Fig. 15.76  Facial picture of the picture with the final restorations

Fig. 15.77  Before and after the secondary restoration

Fig. 15.78  Intra-oral front view at 1-year follow-up

Then we fixed the positioning guide in the mouth to assist the placement of the stackable guide (Fig. 15.101). According to the position of the anchored pin, the first layer of the digital stackable guide, that was, the osteotomy

guide, was placed in the mouth, and the osteotomy was performed (Fig. 15.102). We positioned the second layer of the digital stacking guide, the implant surgical guide, on the osteotomy guide to complete the immediate implantation (Fig. 15.103). We placed the ITI SAC abutment and temporary base above the implant. Then we put the third layer of the digital stacking guide, the immediate restoration, on the temporary base (Fig. 15.104). The light-curing resin sealed the gap between the temporary base and the immediate restoration. The base was placed after being grinded to check the occlusion. Postoperative restorative function examination showed that the extrusion occlusion and the left and right lateral occlusion were good (Figs. 15.105 and 15.106). We performed radiographic examination after implantation to check the position of the implants, and the implants were localized at the ideal sites (Fig. 15.107).

15.2  Typical Cases of Occlusion Reconstruction Aided by the TRS Guide

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Fig. 15.79  The patient filled in the psychological assessment form again. General condition and family history: No special circumstance

Fig. 15.80  Intra-oral view at first visit

6  months after surgery, intraoral scanning was used to record the occlusal surface morphology, and the transitional PMMA temporary restoration was designed and 3D printed based on the scanning data. Before taking the final impression, we designed and printed the impression splinting framework and custom tray according to the preoperative implant design site (Fig. 15.108). Before making the final impression, the impression splinting framework and custom tray were tried in the mouth and the gap between the splint, and the transfer splint was filled with light-curing resin. The custom tray was tried in to

ensure that it would not hinder the transfer rod from emerging (Fig. 15.109). We made the final impression and finished the plaster model (Fig. 15.110). We placed the custom transfer splint on the plaster model to ensure that the relationship between the implants was stable and checked whether the custom impression splinting framework was stable in place (Fig. 15.111). After taking the impression, the transitional PMMA temporary restoration was tried in. The PMMA temporary restoration was checked to ensure that the occlusal relationship was stable (Fig. 15.112). With the transitional temporary prosthesis, the patient had normal facial proportions and a median laugh line. He was satisfied with the shape of the transitional denture (Fig. 15.113). After wearing the transitional temporary prosthesis for 1 month, the patient reported no discomfort and was satisfied with the appearance and function of the transitional denture. So we copied the shape of the transitional temporary restoration and replaced it with the definitive restoration. Proper restoration materials were selected based on the comprehensive consideration of strength and aesthetics. After the doctor-­patient-technician communication, the titanium metal framework and high-translucent zirconia restoration were finally determined (Fig. 15.114).

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Fig. 15.81  The psychological evaluation excluded the negative psychological factors

Fig. 15.82  Extra-oral examination

15.2  Typical Cases of Occlusion Reconstruction Aided by the TRS Guide Fig. 15.83  Examination of TMJ area

Fig. 15.84  Dentition examination

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Fig. 15.85  Periodontal chart

Fig. 15.86  Radiographic examination Fig. 15.87  Diagnosis of the patient

15  Occlusal Reconstruction Under the Guidance of Target Restorative Space

15.3  Clinical Application of Occlusion Adjusting Guide in Occlusal Reconstruction

The definitive restorations were put into the mouth, and the shape and color of the restoration were good, and the occlusal relationship was stable (Fig. 15.115). The patient was followed after wearing the final restoration for 6 months (Figs. 15.116 and 15.117). The patient was satisfied with the shape and color of the restoration. The psychological assessment scale was filled by the patient again, showing that he was more satisfied with the restoration. The patient’s aesthetic evaluation value for the restoration was 9 points (Fig. 15.118). The comparison before and after the prosthetic treatment showed that the prosthesis significantly solved the aesthetic problem, and the patient began to show a confident smile (Fig. 15.119).

Fig. 15.88  Alternative treatment plans

Fig. 15.89  Treatment plan of the patient

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15.3 Clinical Application of Occlusion Adjusting Guide in Occlusal Reconstruction In clinic, some patients with abnormal occlusion, especially those with long-term dentition defect, often need the adjustment of the whole occlusion curve. Such cases can be classified as occlusal reconstruction with insufficient occlusal space. The key point of this kind of occlusal reconstruction lies in how to analyze the occlusal space before treatment to determine a reasonable occlusal curve, how to accurately realize the space design through tooth preparation, and how to perfectly copy the preoperative design to the final restoration. As the abnormal degree of occlusal space varies for different tooth positions, the preoperative design should involve selecting restorative methods of occlusion adjusting, veneer, full crown, and so on for specific tooth. The great advantage of digital technology, being quantifiable and predictable, can greatly reduce the error of space transference. As the carrier of digital spatial analysis, design, transfer, and guidance, TRS guide based on digital technology integrates a variety of restoration methods such as occlusion adjusting, full crown, and so on and realizes the accurate and quantitative replication of spatial design. It is a treatment method that can be easily implemented and whose restorative effect can be expected for the occlusal reconstruction cases with insufficient occlusal space. This section will focus on the digital treatment process

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Fig. 15.90  Three-dimensional image of the upper and lower jaws

Fig. 15.91  Maxillary and mandibular dentition resin models and custom Gothic bow

of occlusal reconstruction with insufficient occlusal space and will mainly introduce the digital clinical workflow of occlusal reconstruction with ­TRS-technique-­based occlusal adjusting guide as well as the design and fabrication of the guide.

15.3.1 Digital Clinical Workflow of Occlusion Reconstruction for Cases with Insufficient Occlusal Space (Fig. 15.120) Before the digital occlusal design, the first question to be answered is “what is insufficient occlusal space,” the second question is “how to obtain occlusal space,” and the last one is

“how to choose a restorative method based on occlusal space.” 1. Assessment of occlusal space: Occlusal space of dentition defect refers to the distance from gingiva of the edentulous area to the central fossa of the opposite tooth. If the occlusal space is greater than or equal to 5 mm, it is recommended to perform conventional implant restoration. If the occlusion space is less than 5 mm, it is thought that the occlusion space is insufficient, and it is necessary to obtain a minimum occlusion space of 5 mm by osteotomy or adjusting the opposite tooth. 2. Analysis of the reasons for insufficient occlusal space. The virtual articulator parameters were set based on the

15.3  Clinical Application of Occlusion Adjusting Guide in Occlusal Reconstruction

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Fig. 15.92  Determine the vertical dimension of occlusion

Fig. 15.93  Confirm the centric relation by a custom Gothic bow (a) Gothic arch tracer fitted in mouth (b) Mandibular movement race (c) Fixed bite record (d) Jaw models arbitrarily mounted on an articulator (e) Duplicated metal-free bite record (f) New record fitted in mouth

actual articulator to obtain a virtual wax-up, and then the virtual wax-up and CBCT are combined to calculate the bone level of the edentulous area. If the insufficient occlusal space is related to the compensatory increase of bone in the edentulous area, it is necessary to carry out the design of digital osteotomy guide and digital implant guide to monitor the intraoperative osteotomy and implantation. If the insufficient occlusal space is found to be related to the elongation of the opposite tooth, the design of virtual wax-up of the opposite tooth will be carried out. In this situation, the occlusal reconstruction

involves not only the design of implant restoration in the dentition defect area but also the design of adjusting the occlusal curve of the opposite tooth. 3. TRS design for occlusal curve adjustment: The design of the occlusal curve adjustment is based on the analysis of the target restorative space. The occlusal curve of virtual wax-up is designed based on Spee curve and opposite occlusal curve. Then the designed occlusal curve is fitted with image of CBCT to calculate the offset which is the preparation amount for TRS. At the same time, evaluate the distance between the expected tooth surface to the

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Fig. 15.94  Mounting on a virtual articulator and creating a virtual patient (a) CBCT reconstruction with passing through hinge axis and Porion (b) The location of hinge axis (Passing through Bergstrom's

Fig. 15.95  Target restoration space design of the patient

point) (c) Virtual patient integrated with digital articulator (d) Prosthetic-driven digital implant planning

15.3  Clinical Application of Occlusion Adjusting Guide in Occlusal Reconstruction

Fig. 15.96  Implant site design

Fig. 15.97  Design of mandibular digital stackable guide

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Fig. 15.98  Design of maxillary digital stackable guide

Fig. 15.99  3D printing resin models of maxillary and mandibular jaws and digital stackable guides

pulp cavity after tooth preparation. If it is less than 1 mm, the preparation for TRS is limited to enamel or the superficial layer of dentin and has little effect on dental pulp. If it is more than 1 mm, considering the possibility of dentin sensitivity or even pulpitis after operation, it is suggested to first give root canal therapy performed with informed consent of the patient and then perform inlay, high inlay, or full crown restoration according to the actual thickness of axial wall. At last, the 3D printing TRS guide is fabricated according to the preparation amount for TRS and the selected restorative method.

15.3.2 A Clinical Case of Designing Occlusion Adjusting Guide 1. Analysis of occlusal curve by intraoral photograph. The patient’s left lower posterior teeth were missing for 3 years. The intraoral left-lateral and right-lateral occlusal views showed that the occlusal curves of the two sides were asymmetric and the teeth opposite to left edentulous area obviously elongated, resulting in insufficient occlusal space and abnormal Spee curve on the left side (Fig.  15.121). According to the above digital clinical

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Fig. 15.100  Extraction of remaining teeth during implant surgery

workflow of occlusal reconstruction for cases with occlusal space deficiency, we calculated the reduction amount of the left maxillary teeth for TRS and designed the left maxillary occlusion adjusting guide. 2. Analysis of the occlusal curve on the extra-oral diagnostic model. The casts were mounted onto the articulator using face bow (Fig. 15.122). We observed and calculated the discrepancy of occlusal curves of left and right sides and recorded the values of protrusive guidance and lateral guidance on the articulator. Then we set parameters for digital articulator according to the solid one and obtained the upper and lower models through the intraoral scan or extra-orally scanning the diagnostic cast. 3. Making the virtual mandibular wax-up. According to the Spee curve of the right side and the parameters of the virtual articulator, the restorations for the edentulous area were designed ensuring that the position of the left restoration would not interfere with the free movement of the upper mandible, and the mandibular digital implant guide was then designed under the guidance of restoration. Based on the designed position of the left mandibular res-

toration, the mandibular movement was simulated on the digital articulator. The ideal maxillary occlusal curve was designed ensuring there would not be any occlusal ­interference, to determine the shape and size of the maxillary target restorations (Fig. 15.123). 4. Determination of reduction amount for TRS.  The designed target prosthesis was fitted with the initial maxillary model to obtain the reduction amount for TRS. The precisely calculated reduction amount can guide the selection of restorative methods. As shown in the figure (Fig. 15.124), the reduction amount for TRS of #27 tooth was less than 1 mm and limited to the mesial buccal cusp, and the occlusal reduction amount for TRS of #25 tooth and #26 tooth was more than 1 mm. Considering the apical situation of #25 tooth and #26 tooth comprehensively, we planned to perform full crown restorations for #25 tooth and #26 tooth after root canal treatment and to adjust the mesial buccal cusp of #27 tooth under the guidance of occlusal adjusting guide. 5. Design of the occlusion adjusting guide (Fig.  15.125). Based on the TRS design theory, combined with the clas-

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Fig. 15.101  Placement of the positioning guide

Fig. 15.102  The first layer of the digital stackable guide: the osteotomy guide

15.3  Clinical Application of Occlusion Adjusting Guide in Occlusal Reconstruction

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Fig. 15.103  The second layer of the digital stackable guide: the implant surgical guide

Fig. 15.104  The third layer of the digital stackable guide: the immediate restoration

sical depth-groove-guiding tooth preparation, guiding grooves were reserved for the occlusion adjusting guide at the axial ridge and main developing groove of the axial wall and the triangular ridge and main developing groove of occlusal surface. As the occlusion adjustment of #27 tooth was limited to the mesial buccal cusp, only two unconnected guiding grooves were reserved in TRS guide. Through the non-uniform thickness design of TRS

guide, the sum of guide thickness and reduction amount for TRS was controlled to be always 4 mm, which realized the integrated design of occlusal adjusting guide and tooth preparation guide. In clinical practice, with HX-6 preparation bur completely inserted into the guide plate, using the classical method of depth-groove-guiding preparation, reduction amount for TRS could be transferred into the mouth.

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Fig. 15.105  Intraoral picture of the immediate restoration

Fig. 15.106  The occlusal movement of the immediate restoration

15.3  Clinical Application of Occlusion Adjusting Guide in Occlusal Reconstruction

Fig. 15.107  Radiographic image after implanting

Fig. 15.108  The three dimensionally printed impression splinting framework and custom tray

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Fig. 15.109  Intra-oral view of the 3D printing impression splinting framework and custom tray

Fig. 15.110  The final impression and the plaster model

15.3  Clinical Application of Occlusion Adjusting Guide in Occlusal Reconstruction

Fig. 15.111  Custom impression splinting framework placed on the model in the mouth

Fig. 15.112  Digital PMMA temporary restoration

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Fig. 15.113  Facial picture of the patient with the temporary restoration

Fig. 15.114  The definitive restoration

Fig. 15.115  The occlusal relationship of definitive restoration

15.3  Clinical Application of Occlusion Adjusting Guide in Occlusal Reconstruction

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Fig. 15.117  Intraoral picture of the mandibular definitive restoration Fig. 15.116  Intraoral picture of the maxillary definitive restoration

Fig. 15.118  Postoperative psychological evaluation

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Fig. 15.119  Facial pictures before and after restoration

The digital clinical pathway of insufficient target restoration space measurament of target restoration space (based on gingiva) ≥5mm regular implant restoration